DE112012005497T5 - Magnetic toner - Google Patents

Abstract

The magnetic toner contains magnetic toner particles containing a binder resin and a magnetic body and inorganic fine particles present on the surface of the magnetic toner particles, wherein the inorganic fine particles present on the surface of the magnetic toner particles comprise metal oxide fine particles, the metal oxide fine particles containing silica fine particles and optionally, titanium oxide fine particles and alumina fine particles, and a content of the silica fine particles is at least 85 mass% based on the total mass of the silica fine particles, the titania fine particles and the alumina fine particles. The coverage rate of the surface of the magnetic toner particles by the inorganic fine particles is in a prescribed range for this magnetic toner; the binder resin is a styrenic resin; the weight average molecular weight and the inertia radius of the magnetic toner are in a prescribed range; and the viscosity of the magnetic toner at 110 ° C is in a prescribed range.

Description

[Technical area]

The present invention relates to a magnetic toner for use in, for example, electrophotographic methods, electrostatic recording methods and magnetic recording methods.

[State of the art]

Printers and copiers changed from analog to digital over the years, and while there was a strong demand for excellent latent image reproducibility and high resolution, there was a strong demand for higher energy savings and higher stability at the same time.

Reducing power consumption in the fusing step of a copier or printer is critical if greater energy savings are considered here.

The implementation of coating fixation to achieve additional reduction in fixation temperature is an effective method for reducing energy consumption. Coating fixation simply supports a reduction in energy consumption because it provides excellent thermal conductivity through the use of a coating.

A problem associated with lowering the fusing temperature with the overcoat fixing is that the peelability between the toner and the overcoat during fixing is poor and the toner does not adhere to the medium, e.g. Paper, can be fixed and the occurrence of development in which a portion of the toner is lifted by the coating, so-called "cold offset", has been frequently observed.

There have been attempts to improve the cold impression by focusing on the fixing unit; z. For example, improvements have been made on the basis of the coating material and on methods that control pressure, pressure distribution, and fixation temperature during fixation.

On the other hand, there were also toner-based attempts to improve the cold impression.

Examples in this regard include lowering the melting point of the release agent and / or adding large amounts of the release agent and reducing the molecular weight of the binder resin and / or reducing the glass transition temperature of the binder resin. These methods tend to improve the cold impression, but additional improvements are needed. In addition, there is a tendency with this toner that the development performance is also lowered, and in particular, a substantial reduction in image stability is liable to occur during long-term use.

As to the improvement of the toner to improve the stability during the long-term use, efforts have been made to change the resistance by, for example, the technical development of the process of attaching external additives to the toner particle and developing the kind of the external additive.

Patent Document 1 discloses a toner for which toner particles are prepared by emulsion aggregation of a styrene resin, a paraffin wax, and so on: the external addition process is carried out, and the ratio between the saturation water content HL under low temperature, low humidity conditions, and saturated water content HH under high temperature - High humidity conditions are brought into a prescribed range.

The control of the water content in this manner actually has a certain effect on the transfer performance and the image density reproducibility; however, no mention is made of cold impression and this was inappropriate for obtaining the effects of the present invention.

In Patent Document 2, stabilization of development transfer steps is designed by controlling the overall coverage of the toner base particle by an external additive, and in fact, a certain effect for a prescribed toner base particle is achieved by controlling a calculated theoretical coverage ratio. However, the actual state of attachment is one external additive is quite different from the value calculated on the assumption that the toner is spherical, and the stability during the long-term use, which is the previously identified problem, does not correlate with this theoretical coverage ratio, and improvement was accordingly required.

[Citation List]

[Patent Literature]

• [PTL 1] Japanese Patent Application Publication No. 2009-229785
• [PTL 2] Japanese Patent Application Publication No. 2007-293043

Summary of the Invention

[Technical problems]

The present invention provides a magnetic toner that can solve the previously identified problems.

Specifically, an object of the present invention is to provide a magnetic toner which can achieve a stable image density during long-term use, and which can prevent the occurrence of cold offset.

[The solution of the problem]

The inventors discovered that the problems are solved by setting the ratio between the coverage of the surface of the magnetic toner particle by the inorganic fine particles and the coverage ratio by inorganic fine particles fixed to the surface of the magnetic toner particle and by setting the molecular weight, the degree of branching and the viscosity at 110 ° C of the magnetic toner can be solved. The present invention has been accomplished on the basis of this discovery. Thus, the present invention will be described as follows:
a magnetic toner comprising: magnetic toner particles comprising a binder resin and a magnetic body; and inorganic fine particles present on the surface of the magnetic toner particles, wherein;
the inorganic fine particles present on the surface of the magnetic toner particles comprise metal oxide fine particles,
wherein the metal oxide fine particles contain silica fine particles and optionally contain titanium oxide fine particles and alumina fine particles, and a content of the silica fine particles is at least 85 mass% based on the total mass of the silica fine particles, the titania fine particles and the alumina fine particles, wherein;
when a coverage ratio A (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles, and a coverage ratio B (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles fixed to the surface of the magnetic toner particles; the magnetic toner has a coverage ratio A of at least 45.0% and not more than 70.0% and a ratio [coverage ratio B / coverage ratio A] of the coverage ratio B to the coverage ratio A of at least 0.50 to not more than 0.85 , and
the binder resin is a styrenic resin;
for a weight average molecular weight (Mw) and a radius of gyration (Rw) measured on the ortho-dichlorobenzene-soluble magnetic toner material using size-exclusion chromatography with multi-angle laser light scattering (SEC-MALLS), the weight average molecular weight (Mw) is at least 5,000 to 5,000 not more than 20,000 and the ratio [Rw / Mw] of this radius of gyration (Rw) to the weight average molecular weight (Mw) is at least 3.0 × 10 ^-3 to not more than 6.5 × 10 ^-3 ; and
the viscosity of the magnetic toner at 110 ° C measured by a flow tester / temperature rise method is at least 5,000 Pa · s to not more than 25,000 Pa · s.

[Advantageous Effects of Invention]

The present invention can provide a magnetic toner which can achieve a stable image density during long-term use and can prevent the occurrence of cold impression.

[Brief Description of the Drawings]

1 Fig. 12 is a graph showing an example of the relationship between the number of particles of silica addition and the coverage ratio;

2 Fig. 12 is a graph showing an example of the relationship between the number of particles of silica addition and the coverage ratio;

3 Fig. 10 is a schematic diagram showing an example of an image forming apparatus;

4 Fig. 10 is a schematic diagram showing an example of a mixing apparatus which can be used for external addition and mixing of inorganic fine particles;

5 Fig. 12 is a schematic diagram showing an example of the structure of a stirring member which can be used in the apparatus for the mixing method;

6 Fig. 15 is a diagram showing an example of the relationship between the ultrasonic dispersion time and the coverage rate; and

7 Fig. 12 is a diagram showing an example of the relationship between the coverage rate and the static friction coefficient.

[Description of the Embodiments]

The present invention will be described in detail below. The present invention relates to a magnetic toner (hereinafter also referred to as "toner") comprising: magnetic toner particles comprising a binder resin and a magnetic body and inorganic fine particles present on the surface of the magnetic toner particles, wherein;
the inorganic fine particles present on the surface of the magnetic toner particles comprise metal oxide fine particles,
wherein the metal oxide fine particles contain silica fine particles and optionally titanium oxide fine particles and alumina fine particles, and a content of the silica fine particles is at least 85 mass% based on a total mass of the silica fine particles, the titania fine particles and the alumina fine particles, wherein;
when a coverage ratio A (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles, and when a coverage ratio B (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles fixed on the surface of the magnetic toner particles , the magnetic toner has a coverage ratio A of at least 45.0% and not more than 70.0%, and a ratio [coverage ratio B / coverage ratio A] of the coverage ratio B to the coverage ratio A of at least 0.50 to not more than 0, 85; and
the binder resin is a styrenic resin;
for a weight average molecular weight (Mw) and a radius of gyration (Rw) measured on the ortho-dichlorobenzene-soluble magnetic toner material using size-exclusion chromatography with multi-angle laser light scattering (SEC-MALLS), the weight average molecular weight (Mw) of at least 5,000 to not is more than 20,000 and the ratio [Rw / Mw] of this radius of gyration (Rw) to the weight average molecular weight (Mw) is at least 3.0 × 10 ^-3 to not more than 6.5 × 10 ^-3 ; and the viscosity of the magnetic toner at 110 ° C measured by a flow tester / temperature rise method is at least 5,000 Pa · s to not more than 25,000 Pa · s.

According to research by the inventors, the use of the above-described magnetic toner can provide a stable image density during the long-term use and can suppress the occurrence of cold impression.

The reasons for the occurrence of cold impression are now considered.

If the behavior is considered during fixation, [1] unfixed toner is first applied to the medium, e.g. As paper loaded. [2] Then, when the unfixed toner is passed through the fixing unit, the toner is melted and deformed, and the releasing agent also migrates to the toner surface, and as a result, the toner particles bonded to each other are anchored on the paper, ie, the medium and the toner is fixed. During this passage of the toner through the fixing nip section, the is formed by the fixing coat and a pressure roll, the driving forces by which the toner is fixed are applied by the application of heat to the toner via the fixing coat from the heat source in the fixing unit, and by applying pressure due to the pressure of e.g. B. the pressure roller during the passage through the Fixierspaltabschnitt. [3] After passing through the fixing nip, the toner is separated from the fixing coat and fixed on the paper.

Meanwhile, with regard to the cause of cold impression, cold impression occurs when, for each of the factors described below, the toner that has passed through the fixing nip is unable to peel off the fixing coat and adhere to the fixing coat.

The factors that result in the appearance of cold impression are now considered. The following may be noted: [1] The case in which the melting of the toner in the fixing nip portion is insufficient, e.g. For example, only toner from the heat source side (fixing coat side) is subjected to melting while toner on the side away from the heat source (medium side) can not melt, resulting in insufficient adhesion to the medium and attachment to the fixing coat; [2] the case in which the toner is subjected to adequate melting in the fixing nip portion, but the migration of the release agent to the toner surface is insufficient, resulting in poor releasability from the fixing coat and attachment to the fixing coat.

Using conventional methods, the inventors have therefore prepared magnetic toners in which to promote melting, deformation, release agent migration. Consequently, a magnetic toner A was prepared by using silica as an external additive for magnetic toner particles in which a large amount of a release agent was added to a binder resin having a low molecular weight and a low glass transition temperature. A magnetic toner B was also prepared in which the amount of silica addition was reduced to further improve the fixing performance.

According to the results, the magnetic toner A had better low-temperature fixability and also an improved cold-printing property as compared with conventional magnetic toners. In addition, the magnetic toner B, while having an even better low-temperature fixability than the magnetic toner A, gave the same results as the magnetic toner A with regard to the cold impression property.

While an improved cold impression characteristic was observed with both magnetic toners, the results were inferior in the cold impression characteristic sought by the inventors. In addition, the image density during the long-term use, which was checked in conjunction with the low-temperature fixability, was given a much poorer result than that of conventional magnetic toners.

When these results of the evaluation of the cold impression characteristic were considered, the cold impression characteristic was not improved even for the magnetic toner B, which was improved to allow even greater promotion of the melting of the release agent than the magnetic toner A. Consequently, it was concluded that factors other than melting • deformation • release agent migration are necessary to improve the cold-printing property of a magnetic toner. In addition, the improvement in the stabilization of image density during long-term use was also necessary.

The inventors therefore conducted concentrated studies to obtain additional improvement in the cold cast to achieve stabilization of image density during long-term use. As a result, it has been found that the previously identified problems can be solved by setting the ratio between the coverage ratio by the inorganic fine particles fixed to the magnetic surface particle area and the coverage rate of the magnetic toner particle surface by the inorganic fine particles and by adjusting the molecular weight. the degree of branching and the viscosity at 110 ° C of the magnetic toner.

First, a summary for the magnetic toner of the present invention includes an improvement of the sharp melting property by providing a reduction in melt viscosity during melting for the magnetic toner of the present invention. The means used herein to achieve viscosity reduction during melting do not use conventional techniques such as molecular weight reduction and / or glass transition temperature reduction Binder resin in the magnetic toner; instead, the reduction in melt viscosity is achieved by controlling the degree of branching for the magnetic toner to a straight-chain type.

In addition, the coverage ratio by the inorganic fine particles fixed on the magnetic toner particle surface is optimized for the magnetic toner of the present invention. With such a magnetic toner, the heat is easily transferred to the magnetic toner; Melting • Deformation • Release agent migration is simplified for the magnetic toner; and an unprecedented improvement is achieved for the peelability of the overcoat layer.

• [1] Zunächst wird hinsichtlich des Zustands des unfixierten Bilds auf dem Medium, z. B. Papier, in der vorliegenden Erfindung angenommen, dass die Oberfläche des unfixierten Bildes (die von dem Medium entfernte Seite; die Seite, die den Fixierüberzug kontaktiert) glatt ist und ein Laden auf dem Medium, z. B. Papier, in einem Zustand auftritt, in welchem der magnetische Toner engstem Packen sich annähert.

The analysis by the inventors will be given below in succession according to the previously described behavior during fixation.

• [1] First, regarding the state of the unfixed image on the medium, e.g. Paper, in the present invention, it is assumed that the surface of the unfixed image (the side remote from the medium, the side which contacts the fixing coat) is smooth, and loading on the medium, e.g. As paper, occurs in a state in which the magnetic toner approaches closest packing.

When this occurs, the optimization of the coverage rate by the inorganic fine particles fixed to the magnetic toner particle surface in the magnetic toner results in formation of, for example, a shell layer by the inorganic fine particles, and as a consequence, the van der Waals force is simply reduced and the attachment force between the magnetic toners is reduced. In addition, it is considered that a deposition effect exists due to the inorganic fine particles. Due to these effects, the aggregation of the magnetic toner is inhibited, and the attachment force to components and the attachment force between the magnetic toners are also easily reduced.

• [2] Wenn dann der nicht fixierte magnetische Toner durch den Fixierspalt geführt wird, wird die Wärme gleichmäßig und wirkungsvoll – auf den magnetischen Toner übertragen, da, wie in [1] beschrieben, die Oberfläche des nicht fixierten Bildes glatt ist und in einem Zustand verbleibt, der sich der engsten Packung annähert. Da zusätzlich in der vorliegenden Erfindung die Verringerung in der Schmelzviskosität während des Schmelzens durch Steuerung des Verzweigungsgrads im magnetischen Toner zu einem linear- bzw. geradkettigen Typ entwickelt wurde, wird die scharfe Schmelzeigenschaft wesentlich über die für einen magnetischen Toner verbessert, der Viskositätsreduktion erzielt durch Techniken, wie etwa Verwendung eines Bindemittelharzes vom verzweigten Typ und Verringerung des Molekulargewichts. Es wird angenommen, dass das Schmelzen • Verformen • Trennmittelauswandern des magnetischen Toners als ein Ergebnis gefördert wird.

As a consequence, the magnetic toner developed on the image-bearing member is subjected to relaxation without aggregation, and as a result, a state close to the closest packing is provided. In addition, it is assumed that at the point where the magnetic toner from the image-bearing member on the medium, for. As paper, is transferred, because the attachment force of the device has been reduced, the transferability is improved and the surface of the unfixed image is smoothed.

• [2] Then, when the unfixed magnetic toner is passed through the fixing nip, the heat is uniformly and efficiently transferred to the magnetic toner because, as described in [1], the surface of the unfixed image is smooth and in one state remains that approaches the closest pack. In addition, in the present invention, since the reduction in the melt viscosity during the melt by controlling the degree of branching in the magnetic toner has been developed into a linear type, the sharp melting property is substantially improved over that for a magnetic toner which achieves viscosity reduction by techniques such as use of a branched-type binder resin and reduction in molecular weight. It is believed that the melting • deformation • release agent migration of the magnetic toner is promoted as a result.

• [3] Mit Blick auf die Notwendigkeit für den magnetischen Toner von dem Fixierüberzug nach dem Durchtreten durch den Fixierspalt freigesetzt zu werden, wird hypothetisch angenommen, dass der Existenzzustand der anorganischen Feinteilchen an der fixierten Bildoberfläche während Abtrennung von dem Fixierüberzug unterschiedlich für den magnetischen Toner der vorliegenden Erfindung zu dem für konventionelle magnetische Toner ist.

In view of the reason, it is considered that the melting of the binder resin is synonymous with the molecular chains which, in a bonded configuration, are entangled in the glassy state, undergoing molecular motion induced therewith, and the molecular chains are then able to merge in free movement to grab. As a consequence, it is believed that the sharp melting property is more easily influenced by the degree of branching than by the molecular weight.

• [3] In view of the need for the magnetic toner to be released from the fixing coat after passing through the fixing nip, it is hypothesized that the state of existence of the inorganic fine particles on the fixed image surface during separation from the fixing coat is different for the magnetic toner of the fixing film This invention is for conventional magnetic toner.

It is therefore hypothesized that, unlike conventional magnetic toners which remain in a state in which the release agent and the binder resin are exposed on the fixed image surface, the magnetic toner of the present invention remains in a state in which the release agent and the release agent high-coverage, fixed inorganic fine particles are present on the fixed image surface.

This is believed to result in a substantial increase in releasability from the fixing coat and an improvement in the cold-print property. As a reason for this improvement in the cold-printing property, a synergistic effect is believed to be exhibited between the high sharp melting property of the magnetic toner of the present invention and the high-coverage, fixed inorganic small particles.

In summary of the foregoing, it is believed that the control imparted to the coverage ratio by the fixed inorganic fine particles in the invention provides a smooth surface for the unfixed image and results in loading of the unfixed magnetic toner onto the medium, e.g. As paper results in a state in the approach to tightest packing. A high sharp-melting property is generated because this unfixed image can uniformly and effectively receive heat from the fixing unit and because a low-melt viscosity during melting is obtained by controlling the molecular weight and branching degree of the magnetic toner. Immediate melting • deformation • release agent migration is enabled as a result for the magnetic toner of the present invention. Further, the high sharp-melting property exhibited by the toner of the present invention facilitates maintenance of the state of the magnetic toner surface at the time of separating the magnetic toner from the fixing coat. Therefore, a state is provided in which the high-coverage, fixed inorganic fine particles and the release agent are present, resulting in a substantial increase in releasability from the fixing coat. It is believed that the cold impression is improved due to this synergistic effect.

It was further shown that the stability during long-term use could also be obtained with the magnetic toner of the present invention. The inventors believe that the reasons are as follows.

A ratio is specified for the magnetic toner of the present invention by the coverage ratio by inorganic fine particles fixed to the magnetic toner particle surface (coverage ratio B) and the coverage rate of the magnetic toner particle surface by the inorganic fine particles (coverage ratio A). As a consequence, the above-described aggregative behavior between the magnetic toners is lowered, and the attaching force between the magnetic toner and the devices is lowered, which hinders the exercise of excessive stress and the deterioration of the magnetic toner as a consequence during tribological charge in the developing device inhibits.

In addition, because the state of fixing to the magnetic toner particle surface is generated more completely than in the conventional state of inorganic fine particle cover, the burying of the inorganic fine particles in the magnetic toner is inhibited during the long-term use. In addition, changes in the existence state of the inorganic fine particles during the long-term use can be alleviated by providing the state of fixing to the magnetic toner particle surface.

Further, a reduction in melt viscosity during melting for the magnetic toner of the present invention by controlling the molecular weight and branching degree has been technically developed, but the molecular weight is larger than that for conventional toners which achieves a reduction in viscosity by lowering the molecular weight and / or reducing the glass transition temperature to have. The degree of branching of the magnetic toner is of the straight-chain type, but because of the high molecular weight, the strength is increased in the range less than or equal to the glass transition temperature of the magnetic toner as compared with a magnetic toner of the reduced molecular weight type is. Therefore, the toner deterioration is suppressed even during the long-term use, and thus the image stability is improved.

It is hypothesized that the toner deterioration is suppressed during the long-term use and the image stabilization is achieved by adjusting this ratio between the coverage ratio due to the inorganic fine particles fixed to the magnetic toner particle surface and the coverage of the inorganic toner particle surface by the inorganic fine particles and adjusting the molecular weight and the degree of branching of the magnetic toner.

The toner of the present invention will be specifically described below

Further, when a coverage ratio A (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles, and when the coverage ratio B (%) is the coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles fixed to the surface of the magnetic toner particles For the magnetic toner of the present invention, it is critical that the coverage ratio A is at least 45.0% and not more than 70.0%, and that the ratio [coverage ratio B / coverage ratio A, hereinafter also simply referred to as B / A ] the coverage ratio B to the coverage ratio A is at least 0.50 and not more than 0.85. The coverage ratio A is preferably at least 45.0% and not more than 65.0%, and B / A is preferably at least 0.55 and not more than 0.80.

Since the coverage ratio A is high at least 45.0% in the magnetic toner of the present invention, the van der Waals force between the magnetic toner and components becomes small, and the attachment force between the magnetic toners and devices is simply attenuated and an improvement in image stabilization during the long-term use and in the cold impression property is thereby made possible.

On the other hand, the inorganic fine particles must be added in a large amount to bring the coverage ratio A to greater than 70.0%. Even if an external addition method could be invented for it, the thermal performance during fixation by degraded inorganic fine particles would be degraded, and the releasability from the fixing coat would be degraded and the cold impression property would deteriorate as a result. Here, the coverage ratio A (%) and B / A can be obtained by the following methods.

The coverage rate A is a coverage rate which also includes the easy-peelable inorganic fine particles, while the coverage ratio B is the coverage ratio due to the inorganic fine particles fixed on the surface of the magnetic toner particles that are not released in the release process described below. It is assumed that the inorganic fine particles represented by the covering rate B are fixed in the surface of the magnetic toner particles in a semi-embedded state, and hence are not subjected to peeling even if the magnetic toner is shattered on the developing sleeve or on an electrostatic latent image undergoes load-bearing component.

On the other hand, the inorganic fine particles represented by the coverage ratio A include both the above-described fixed inorganic fine particles and inorganic fine particles which are present in the upper layer and have a relatively high degree of freedom. The presence of the inorganic fine particles present in the midst of the magnetic toners and between the magnetic toners and each component affects the reduction in aggregability and the reduction in the adhesive strength. To address this reduction, an increase in the coverage ratio A appears to be important.

As described above, the magnetic toner of the present invention has excellent component releasability. This point is considered in detail below from the perspective of the van der Waals force and the electrostatic force.

First, the van der Waals force (F) generated between a flat plate and a particle is represented by the following equation. F = H × D / (12Z ² )

Here, H is the Hamaker constant, D is the diameter of the particle and Z is the distance between the particle and the flat plate.

With reference to Z, it is generally considered that attractive force acts at large distances and repulsive force acts at very small distances, and Z is treated as a constant since it has no relation to the state of the surface of the magnetic toner particles.

According to the preceding equation, the van der Waals force (F) is proportional to the diameter of the particles in contact with the flat plate. When transferred to the surface of the magnetic toner, the van der Waals force (F) for an inorganic fine particle in contact with the flat plate having its smaller particle size is smaller than that for a magnetic toner particle in contact with the flat plate. That is, the van der Waals force is smaller in the case of contact by the intermediate piece of the fine inorganic particle provided as an external additive, in the case of direct contact between the magnetic toner particle and each component (a developing sheet, an electrostatic latent image bearing member, and a fixing coat).

In addition, the electrostatic force can be considered as a reflection force. It is known that a reflection force is directly proportional to the square of the particle charge (q) and inversely proportional to the square of the distance.

In the case of charging a magnetic toner, the surface of the magnetic toner particle is not the inorganic fine particle bearing the charge. Due to this, the reflection force decreases as the distance between the surface of the magnetic toner particle and the flat plate (here, the fixing coat) grows larger.

That is, in the case of the magnetic toner surface, when the magnetic toner particle comes into contact with the flat plate through the intermediate of the inorganic fine particles, a space is formed between the flat plate and the surface of the magnetic toner particle, and as a result, the reflection force is reduced ,

As described in the foregoing, the van der Waals force and the reflection force generated between the magnetic toner and the fixing coat are reduced by the presence of inorganic fine particles on the surface of the magnetic toner particles and by the magnetic toner having the fixing coat with the inorganic grains interposed therebetween Fine particles come into contact. That is, the attachment force between the magnetic toner and the fixing coat is reduced.

Whether the magnetic toner particle directly contacts or is in contact with the fixing coat by the intermediate piece of the inorganic fine particles depends on the amount of the inorganic fine particles coating the surface of the magnetic toner particle, that is, the amount of the inorganic fine particles. H. from the coverage rate by the inorganic fine particles.

It is believed that the opportunity for direct contact between the magnetic toner particles and the fixing coat is reduced at a high coverage ratio with the inorganic fine particles, making it difficult for the magnetic toner to adhere to the fixing coat. On the other hand, with a low coverage ratio by the inorganic fine particles, the magnetic toner easily adheres to the fixing coat, and the peeling property of the fixing coat is lowered.

On the other hand, B / A is at least 0.50 to not more than 0.85, inorganic fine particles fixed to the magnetic toner particle surface are present to a certain degree, and in addition, inorganic fine particles are placed in an easy-release state (a state an appearance separated from the magnetic toner particles) are also present thereon in an advantageous amount. It is believed that a bearing-like effect is presumably generated by the releasable inorganic fine particles sliding against the fixed inorganic fine particles, and then the aggregative forces between the magnetic toners are then substantially reduced. Due to this, as previously noted, the surface of the unfixed image is smoothed and a state close to the closest packing can be set, and the heat from the fixing unit can then be uniformly and efficiently discharged to the magnetic toner. In addition, excessive stress on the magnetic toner is eliminated by the storage effect, and as a consequence, the image stability during the long-term use is substantially improved.

According to the results of investigations by the inventors, it has been found that this storage effect and the above-described adjuvant-reducing effect are maximized when both the fixed inorganic fine particles and the easily-releasable inorganic fine particles have relatively small inorganic fine particles having a number average particle diameter (FIG. D1) of the primary particles of about not more than 50 nm. Accordingly, the coverage ratio A and the coverage ratio B were calculated by focusing on the inorganic fine particles having a number average particle diameter (D1) of the primary particles of not more than 50 nm.

In addition, in the present invention, the coefficient of variation of the coverage ratio A is preferably 10.0%, and more preferably not more than 8.0%. Setting a variation coefficient of the coverage ratio A of not more than 10.0% means that the coverage ratio A between magnetic toner particles and within the magnetic toner particle is very uniform.

The coefficient of variation of the coverage ratio A is preferably not more than 10.0% because it makes the generation of peelability from the fixing coat more simplified by providing the fixed inorganic fine particles more uniformly on the fixed image surface after passage through the fixing nip as described previously.

When the coefficient of variation of the coverage ratio exceeds 10.0%, the state of coverage of the magnetic toner surface becomes uneven, impairing the ability to reduce the aggregative forces between the toners.

There are no particular limitations on the technique for bringing the coefficient of variation of the coverage ratio to 10.0% or less, but the use of the external addition device and the technique described below is preferable, which is capable of a high degree of propagation of the Metal oxide fine particles, e.g. Silica fine particles, over the surface of the magnetic toner particles.

With respect to the covering rate of the inorganic fine particles, assuming that the inorganic fine particles and the magnetic toner have a spherical shape, a theoretical coverage ratio can be calculated by using the equation described in Patent Document 2, for example. However, there are also many examples in which the inorganic fine particles and / or the magnetic toner have no spherical shape, and in addition, the inorganic fine particles may also be present in an aggregated state on the toner particle surface. As a consequence, the theoretical coverage rate derived using the technique indicated does not apply to the present invention.

The inventors therefore conducted observation of the magnetic toner surface with the scanning electron microscope (SEM) and determined the coverage ratio for the actual coverage of the magnetic toner particle surface by the inorganic fine particles.

As an example, the theoretical coverage ratio and the actual coverage ratio for blends were prepared by adding various amounts of silica fine particles (particle number of silica addition) to 100 parts by weight of the magnetic toner particles (magnetic body content = 43.5 mass%) provided by a pulverization method and a volume-average particle diameter (Dv) of 8.0 μm, determined (see 1 and 2 ). Silica fine particles having a volume average particle diameter (Dv) of 15 nm were used for the silica fine particles.

For the calculation of the theoretical coverage ratio, 2.2 g / cm ^{3 was used} for the true density of the silica fine particles; 1.65 g / cm ³ was used for the true density of the magnetic toner; and monodisperse particles having a particle diameter of 15 nm and 8.0 μm were taken as the silica fine particles and the magnetic toner particles, respectively.

Like in the 1 the theoretical coverage ratio exceeds 100% when the addition amount of the silica fine particles is increased. On the other hand, the actual coverage ratio varies with the addition amount of the silica fine particles but does not exceed 100%. This is because silica fine particles are present as aggregates on the magnetic toner surface to a certain extent, or due to a large effect of silica fine particles which are not spherical.

Moreover, according to the investigations by the inventors, it was found that even with the same addition amount of the silica fine particles, the coverage ratio fluctuated with the external addition technique. That is, it is impossible to determine the coverage ratio solely from the addition amount of the silica fine particles (see 2 ). Here, the external addition condition A refers to mixing at 1.0 W / g for a processing time of 5 minutes using the apparatus in the US patent application Ser 4 , The external addition condition B refers to mixing at 4000 rpm. for a processing time of 2 minutes using a FM10C Henschel mixer (from Mitsui Miike Chemical Engineering Machinery Co., Ltd.).

For the reasons stated above, the inventors used the inorganic fine particle coverage ratio obtained by SEM observation of the magnetic toner surface.

In addition, as previously noted, it is believed that the attachment force to a component can be reduced by increasing the coverage ratio by the inorganic fine particles. Therefore Tests were carried out for the attachment force with a component and the coverage rate of the inorganic fine particles.

The relationship between the coverage ratio for the magnetic toner and the attachment force with a component was indirectly derived by measuring the static friction coefficient between an aluminum substrate and spherical polystyrene particles having different coverage ratios by silica fine particles.

Specifically, the relationship between the coverage rate and the static friction coefficient was determined by using spherical polystyrene particles (weight average particle diameter (D4) = 7.5 μm) having different coverage ratios (certain coverage ratio by SEM observation) by silica fine particles.

More specifically, spherical polystyrene particles to which silica fine particles were added were pressed on an aluminum substrate. The substrate was moved left and right while the contact pressure was changed, and the static friction coefficient was calculated from the resulting load. This was done for the spherical polystyrene particles at a different coverage ratio and the obtained relationship between the coverage rate and the static friction coefficient is shown in FIG 7 shown.

It is believed that the static coefficient of friction determined in the prior art correlates with the sum of the van der Waals and reflection forces acting between the spherical polystyrene particles and the substrate. According to 7 There occurs a tendency in which the static friction coefficient decreases with the increase in the coverage ratio by the silica fine particles. That is, it is concluded that a magnetic toner having a high coverage ratio by inorganic fine particles also has a low attachment force to a component.

The binder resin for the magnetic toner of the present invention is a styrenic resin.

The use of a styrenic resin for the binder resin enables the ratio [Rw / Mw] between the radius of gyration (Rw) and the weight average molecular weight (Mw) measured using size exclusion chromatography with a multi-angle laser light scattering (SEC-MALLS) which is a characterizing feature of toner according to the invention and an indication of the degree of branching - to set in the desired range.

Specifically, the styrenic resin can be exemplified by polystyrene and by styrenic copolymers such as styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-methylacrylate copolymers, styrene-ethylacrylate copolymers, styrene-butylacrylate copolymers, styrene-octylacrylate copolymers , Styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-butyl methacrylate copolymers, styrene-octyl methacrylate copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-maleic acid copolymers, and styrene-maleate ester copolymers. A single one of them may be used or a plurality may be used in combination.

Styrene-butyl acrylate copolymers and styrene-butyl methacrylate copolymers are particularly preferred from the foregoing because they aid in easy adjustment of the degree of branching and resin viscosity and, as a consequence, facilitate the balanced coexistence of developing properties and cold impression properties.

In addition, while the binder resin used in the magnetic toner of the present invention is a styrene resin, the following resins may be used in combination with it to the extent that the effects of the present invention are not impaired. For example, a polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin or polyacrylic acid resin may be used, and a single one of them may be used or a combination of a plurality thereof may be used.

The monomers for the preparation of this styrenic resin can be exemplified by the following:
styrene; Styrene derivatives, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p- tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene; unsaturated monoolefins, such as such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene and isoprene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; Vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; aliphatic α-methylene monocarboxylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; Acrylate esters such as methylacrylate, ethylacrylate, n-butylacrylate, isobutylacrylate, propylacrylate, n-octylacrylate, dodecylacrylate, 2-ethylhexylacrylate, stearylacrylate, 2-chloroethylacrylate, and phenylacrylate; Vinyl ethers, such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone; vinyl naphthalenes; and derivatives of acrylic acid and methacrylic acid, such as acrylonitrile, methacrylonitrile and acrylamide.

Additional examples are unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid and mesaconic acid; unsaturated dibasic acid anhydrides such as maleic anhydride, citraconic anhydride, itaconic anhydride and alkenyl succinic anhydride; the half esters of unsaturated dibasic acids such as the methyl half ester of maleic acid, the ethyl half ester of maleic acid, the butyl half ester of maleic acid, methyl half ester of citraconic acid, ethyl half ester of citraconic acid, butyl half ester of citraconic acid, methyl half ester of itaconic acid, methyl half ester of alkenyl succinic acid, methyl half ester of fumaric acid and methyl half ester of mesaconic; unsaturated dibasic acid esters such as dimethyl maleate and dimethyl fumarate; α, β-unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid and cinnamic acid; α, β-unsaturated acid anhydrides, such as crotonic anhydride and cinnamic anhydride, as well as the lower fatty acid anhydrides with α, β-unsaturated acids; and monomers containing the carboxyl group, such as alkenylmalonic acid, alkenylglutaric acid and alkenyladipic acid and their acid anhydrides and monoesters.

Additional examples include acrylate esters and methacrylate esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate and monomers containing the hydroxy group, such as 4- (1-hydroxy-1-methylbutyl) styrene and 4- (1-hydroxy) 1-methylhexyl) styrene.

The styrene resin used in the binder resin in the magnetic toner of the present invention may have a crosslinked structure as provided by crosslinking with a crosslinking agent containing two or more vinyl groups. The crosslinking agent used herein may be exemplified by the following:
Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene;
Diacrylate compounds in which the linkage is carried out by an alkyl chain such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and compounds provided by replacing the acrylate in the preceding compounds with methacrylate;
Diacrylate compounds in which the linkage is carried out by an alkyl chain containing ether bonds such as diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate and compounds provided by replacing the acrylate in the foregoing compounds with methacrylate;
Diacrylate compounds in which linking is by a chain containing an aromatic group and an ether linkage, such as polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis ( 4-hydroxyphenyl) propane diacrylate and compounds provided by replacing the acrylate in the foregoing compounds with methacrylate;
The polyester type acrylate compounds, e.g. MANDA (product name, Nippon Kayaku Co., Ltd.);
Multifunctional crosslinking agents such as pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, and compounds provided by replacing the acrylate in the foregoing compounds with methacrylate; as well as triallyl cyanurate and triallyl trimellitate.

The crosslinking agent is used in terms of 100 parts by mass of the other monomer component, preferably from 0.01 to 10 parts by mass, and more preferably from 0.03 to 5 parts by mass.

Of these crosslinked monomers, aromatic divinyl compounds (especially divinylbenzene) and diacrylate compounds in which linkage is through a chain containing an aromatic group and an ether linkage are crosslinking monomers suitable for use in the binder resin from the standpoint of fixing performance and Imprint resistance ("offset resistance") are preferred.

The polymerization initiator used in the preparation of the styrene resin in question can be exemplified by 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-azobis). dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), dimethyl 2,2'-azobisisobutyrate, 1,1'-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) isobutyronitrile, 2,2'-azobis (2 , 4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2,2-azobis (2-methylpropane), ketone peroxides (e.g., methyl ethyl ketone peroxide, acetylacetone peroxide and cyclohexanone peroxide), 2,2- bis (t-butyl peroxy) butane, t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, isobutyl peroxide , Octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-toluoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propylpe roxydicarbonate, di-2-ethoxyethyl peroxycarbonate, dimethoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxylaurate, t-butyl peroxy Butyl peroxybenzoate, t-butyl peroxy isopropyl carbonate, di-t-butyl peroxy isophthalate, t-butyl peroxyallyl carbonate, t-amyl peroxy-2-ethyl hexanoate, di-t-butyl peroxyhexahydroterephthalate and di-t-butyl peroxy azelate.

For a weight average molecular weight (Mw) and a radius of gyration (Rw) measured on the orthodichlorobenzene insoluble matter of the magnetic toner of the present invention using size exclusion chromatography with a multi-angle laser light scattering (SEC-MALLS), the weight average molecular weight (Mw) of at least 5,000 to not more than 20,000, and the ratio [Rw / Mw] of the radius of gyration (Rw) to the weight average molecular weight (Mw) is from at least 3.0 × 10 ^-3 to not more than 6.5 × 10 ^-3 , The weight average molecular weight (Mw) is preferably from at least 5,000 to not more than 15,000, while the ratio [Rw / Mw] of the radius of gyration (Rw) to the weight average molecular weight (Mw) is preferably from at least 5.0 × 10 ^-3 is not more than 6.5 × 10 ^-3 . The unit of inertia radius (Rw) is "nm".

Here, the mean square radius (Rg ² ) is a value generally representing the expansion per molecule, and the value [Rw / Mw] is given by dividing the radius of gyration Rw (the square root of the mean square radius (Rw = (Rg ² ) ^{1 / 2} )) by the weight average molecular weight (Mw) is taken to represent the degree of branching per molecule. Accordingly, it is considered that the smaller [Rw / Mw], the smaller the expansion per molecular weight, and as a consequence, the greater the degree of branching in the molecule; conversely, the larger [Rw / Mw], the greater the increase in molecular weight, and as a consequence, a straight-chain molecule is indicated.

The mean square radius and weight average molecular weight determined by SEC-MALLS will now be described. The molecular weight distribution measured by SEC is based on molecular size, while the intensity is the amount of molecule present. In contrast, the utilization of the light scattering intensity obtained by SEC-MALLS (SEC used as the separation technique) is coupled with a multi-angle laser light scattering detector, which enables the measurement of weight-average molecular weight (Mw) and molecular expansion (mean square radius) determination a molecular weight distribution that is not based on molecular size.

In the conventional SEC, the molecular weight is measured by passing the molecules to be measured through a column, whereby they are subjected to a molecular sieving action during this time and eluted in order starting from molecules having a larger molecular weight size. In this case, in a linear polymer and a branched polymer having the same molecular weight, the former elutes faster because it has a larger molecular size in the solution. Accordingly, the molecular weight measured by SEC for a branched polymer is generally smaller than the actual molecular weight. On the other hand, the light scattering technique used in the present invention uses the Rayleigh scattering of the measured molecules. In addition, by performing the measurement, the dependence of the intensity of the scattered light on the angle of incidence of the light and the sample concentration and performing an analysis using z. For example, the Zimm or Berry method, a molecular weight (absolute molecular weight) that is closer to the actual molecular weight for linear polymers and all molecular configurations of a branched polymer are determined. In the present invention, the average square radius (Rg ² ) and the weight average molecular weight (Mw) were derived based on the absolute molecular weight by measuring the intensity of the scattered light using the SEC-MALLS measuring procedure described below and analyzing the relationship between the Zimm equation, below, using a Debye plot. A Debye plot is a graph in which K * C / R (θ) is plotted on the y-axis and sin ² (θ / 2) is plotted on the x-axis, and the weight average molecular weight (Mw) can be calculated from the intercept of the y-axis and the mean square radius (Rg ² ) can be calculated from the inclination.

However, since Mw and Rg ² are calculated for the ingredients at each elution time, their average values must be further calculated to obtain Mw and Rg ² for the sample as a whole.

K:

optische Konstante

C:

Polymerkonzentration (g/mL)

R(θ):

relative Intensität des gestreuten Lichts beim Streuungswinkel θ

Mw:

gewichtsbezogenes mittleres Molekulargewicht

P(θ):

Faktor, der die Winkelabhängigkeit des gestreuten Lichts zeigt P(θ) = P(θ)/R₀ = 1 – <Rg2>[(4π/λ)sin(θ/2)]²/3

<Rg²>:

mittlerer Quadratradius

λ:

Wellenlänge (nm) des Laserlichts in der Lösung

When the measurements are made using the instrument described below, the values for the radius of gyration (Rw) and the weight average molecular weight (Mw) for the sample as a whole are obtained as a direct output from the instrument. [Equation 1]

K:

optical constant

C:

Polymer concentration (g / mL)

R (θ):

relative intensity of the scattered light at the scattering angle θ

Mw:

weight average molecular weight

P (θ):

Factor showing the angular dependence of the scattered light P (θ) = P (θ) / R ₀ = 1 - <Rg 2> [(4π / λ) sin (θ / 2)] ^2/3

<Rg ² >:

mean square radius

λ:

Wavelength (nm) of the laser light in the solution

Orthodichlorobenzene is used for the extraction solvent in the present invention.

The reason for this is that correlation is seen for the magnetic toner of the present invention between the ortho-dichlorobenzene-soluble material and the behavior during fixation.

It is believed that this is because of the ability of orthodichlorobenzene - which has a high extraction capacity because it is a polar solvent, and because it permits extraction at high temperatures, e.g. B. 135 ° C, due to its high boiling point of 180 ° C - to extract a broad molecular weight band, which is relevant for melting during fixation.

It is critical in the present invention that the weight average molecular weight (Mw) measured on the ortho-dichlorobenzene-soluble magnetic toner material using size-exclusion chromatography with a multi-angle laser light scattering (SEC-MALLS) is at least 5,000 to not more than 20,000. The viscosity can be reduced when heat is given to the magnetic toner when the weight average molecular weight (Mw) is not more than 20,000. As a consequence, melting easily occurs during fixing and the cold impression is improved. In addition, if the weight average molecular weight (Mw) is at least 5,000, then the magnetic toner has high elasticity, and the stabilization during the long-term use can be improved as a consequence. The fixed inorganic fine particles may also assume a more uniform presence on the fixed image surface after passing through the fixation rod, which, in consequence, improves the peelability of the fixing coat.

If this weight average molecular weight (Mw) is larger than 20,000, the classification of the magnetic toner becomes difficult and the fixing performance deteriorates. On the other hand, when the weight average molecular weight (Mw) is less than 5,000, the elasticity of the magnetic toner tends to decrease, and the toner is easily deformed during long-term use, and as a consequence, the density and image quality are liable to decrease.

As previously stated, the toner of the present invention also has a ratio [Rw / Mw] of the radius of gyration (Rw) to the weight average molecular weight (Mw) of at least 3.0 × 10 ^-3 to not more than 6.5 × 10 ^-3, and more preferably from 5.0 × 10 ^-3 to not more than 6.5 × 10 ^-3 .

The setting of an Rw / Mw of at least 3.0 × 10 ^-3 indicates a linear molecular structure, and, as noted above, serves to improve the sharp melting property and the cold impression characteristic. In particular, Rw / Mw is more preferably brought to at least 5.0 × 10 ^-3 because it more easily provides a larger improvement in sharp melting property.

When Rw / Mw is smaller than 3.0 × 10 ^-3 , this indicates a branch-type molecular structure and results in a reduction in sharp melting property. The density during long-term use tends to be somewhat reduced when Rw / Mw is greater than 6.5 × 10 ^-3 .

The weight average molecular weight (Mw) can be controlled here in the range described above by adjusting the type of the amount of addition of the reaction initiator, the polymerization reaction temperature and the vinyl monomer concentration in the dispersion medium during the polymerization reaction.

On the other hand, Rw / Mw can be controlled in the prescribed range by adjusting the kind and amount of addition of the reaction initiator, the polymerization reaction temperature, the vinyl monomer concentration in the dispersion medium during the polymerization reaction and the kind and amount of addition of a transfer agent and by adding Example, a polymerization inhibitor.

Known chain transfer agents can be used as the aforementioned chain transfer agent. Examples are mercaptans such as t-dodecylmercaptan, n-dodecylmercaptan, n-octylmercaptan, etc., and halogenated hydrocarbons such as carbon tetrachloride, carbon tetrabromide, etc.

This chain transfer agent can be added before the start of the polymerization and during the polymerization. The amount of the chain transfer agent addition expressed by 100 parts by mass of the vinyl monomer is preferably from 0.001 to 10 parts by mass, and more preferably from 0.1 to 5 parts by mass.

In the present invention, the viscosity of the magnetic toner at 110 ° C, measured by a flow tester / temperature rise method, is from at least 5,000 Pa · s to not more than 25,000 Pa · s. This viscosity at 110 ° C is more preferably from at least 5,000 Pa · s to not more than 20,000 Pa · s.

As for the cold impression characteristic, as previously noted, during the course of the concentrated investigations, the inventors found out that among the properties of the magnetic toner, the viscosity of a magnetic toner at high temperatures of at least 100 ° C correlates with the cold impression property. Within this, a correlation was confirmed by the viscosity at 110 ° C for the coating fixation, which is the preferred fixing method in the present invention. When considering how 110 ° C fits in the fixing process, it is considered that it corresponds to the temperature of the magnetic toner at the fixing nip and the temperature at the time of peeling off the coating film after passing through the fixing nip.

When this viscosity at 110 ° C is not more than 25,000 Pa · s, the magnetic toner may then be subjected to melting, plasticizing, deformation, etc. on the reflected column, and as a consequence, the fixing performance is increased and the cold impression characteristic is improved.

If this viscosity at 110 ° C at least 5000 Pa · s, then the viscosity of the magnetic toner itself is relatively high due to which a satisfactory adhesion to the media, for. As paper, easily achieved. As a result, the release from the fixing coat after passage through the fixing nip is simplified, and the cold impression property is improved.

When this viscosity at 110 ° C is less than 5,000 Pa · s, the release from the fixing coat is impaired, resulting in a deterioration in the cold impression property and / or the warm impression property, which is a problem when the fixing unit is adequately heated , On the other hand, when the viscosity at 110 ° C exceeds 25,000 Pa · s, the fixing performance tends to be poor, and the cold impression property deteriorates.

This viscosity at 110 ° C can be controlled in the range specified above by adjusting the weight average molecular weight (Mw) of the binder resin and the ratio [Rw / Mw] for the binder resin of the radius of gyration (Rw) to the weight average molecular weight (Mw) and by adjusting the type and amount of addition of the release agent.

From the viewpoint of simply achieving a balanced coexistence between the storability and the low-temperature fixability, the binder resin of the present invention preferably has a glass transition temperature (Tg) of 40 ° C to 70 ° C, and more preferably 50 ° C to 70 ° C. The shelf life is slightly improved when the Tg is at least 45 ° C, because the low-temperature fixability is an improvement trend when the Tg is not more than 70 ° C, and therefore they are preferred.

The magnetic body present in the magnetic toner of the present invention can be exemplified by iron oxides such as magnetite, maghemite, ferrite, etc .; Metals such as iron, cobalt and nickel; and alloys and mixtures of these metals with metals such as aluminum, copper, magnesium, tin, zinc, beryllium, calcium, manganese, selenium, titanium, tungsten and vanadium.

The number-average particle diameter (D1) of the primary particles of this magnetic body is preferably not more than 0.50 μm, and more preferably from 0.05 μm to 0.30 μm.

This magnetic body preferably has the following magnetic properties for the application of 795.8 kA / m: a coercive force (HL) preferably from 1.6 to 12.0 kA / m; a magnetization strength (σ _s ) preferably from 50 to 200 Am ² / kg, and more preferably from 50 to 100 Am ² / kg; and a residual magnetization (σ _r ) of preferably 2 to 20 Am ² / kg.

The magnetic toner of the present invention preferably contains at least 35% by mass to not more than 50% by mass of the magnetic body, and more preferably contains from at least 40% by mass to not more than 50% by mass.

If the content of the magnetic body in the magnetic toner is less than 35 mass%, the magnetic attraction to the magnetic roller in the developing sleeve will decrease and a tendency for fogging to be generated.

On the other hand, when the content of the magnetic body exceeds 50 mass%, the developing performance shows a decreasing tendency.

The content of the magnetic body in the magnetic toner can be measured, for example, by using a Q5000IR TGA thermal analyzer from PerkinElmer Inc. Concerning the measuring method, the magnetic toner is heated from normal temperature to 900 ° C under a nitrogen atmosphere at a rate of temperature rise of 25 ° C / minute: the mass loss of 100 to 750 ° C is adopted as the component provided by subtracting the magnetic Body of the magnetic toner and the residual mass is taken as the amount of the magnetic body.

A charge control agent is preferably added to the magnetic toner of the present invention. The magnetic toner of the present invention is preferably a negative-charging toner.

Organometallic complex compounds and chelate compounds are effective as negative charge charge agents and can be exemplified by monoazo metal complex compounds; Acetylacetone-metal complex compounds and metal complex compounds of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids.

Specific examples of commercially available products are Spilon Black TRH, T-77 and T-95 (Hodogaya Chemical Co., Ltd.) and BONTRON (Registered Trade Mark) S-34, S-44, S-54, E-84, E -88 and E-89 (Orient Chemical Industries Co., Ltd.).

A single one of these charge control agents may be used, or two or more may be used in combination. From the viewpoint of the amount of charge of the magnetic toner, these charge control agents are used in terms of 100 parts by mass of the binder resin, preferably from 0.1 to 10.0 parts by mass, and more preferably from 0.1 to 5.0 parts by mass.

The magnetic toner of the present invention contains a release agent. A hydrocarbon wax, e.g. For example, a low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, paraffin wax, etc. are preferred for the release agent for the high releasability and ease of dispersion that it provides in the magnetic toner.

The reason why hydrocarbon waxes are preferable is that they simply have a lower compatibility with the binder resin than those of e.g. Ester wax, which, in consequence, interferes with compatibility with the binder resin when melting occurs during fixing, thereby facilitating the appearance of peelability. Therefore, the detachability of z. B. improves the fixation and the occurrence of the cold impression is inhibited.

In addition, a single selection of two or more selections of the following waxes may be used in combination as necessary in small amounts. The following are provided as examples.

Examples include the oxides of aliphatic hydrocarbon waxes, such as oxidized polyethylene wax and its block copolymers; Waxes in which the main ingredient is a fatty acid ester, such as carnauba wax, sasol wax and montan acid ester waxes; and products provided by the partial or complete deacidification of fatty acid esters such as deacidified carnauba wax. Additional examples are as follows: saturated straight-chain fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as brassidic acid, eleostearic acid and parinaric acid; saturated alcohols such as stearyl alcohol, aralkyl alcohols, behenyl alcohol, carnaubyl alcohol, ceryl alcohol and melissyl alcohol; long-chain alkyl alcohols; polyhydric alcohols, such as sorbitol; Fatty acid amides such as linoleic amide, oleamide and lauramide; saturated fatty acid bisamides such as methylenebisstearamide, ethylenebiscapramide, ethylenebislauramide and hexamethylenebisstearamide; unsaturated fatty acid amides such as ethylenebisoleamide, hexamethylenebisoleamide, N, N'-dioleyladipamide and N, N-dioleylsebacamide; aromatic bisamides such as m-xylenebisstearamide and N, N-distearylisophthalamide; Fatty acid metal salts (commonly known as metal soaps), such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate; Waxes provided by grafting onto an aliphatic hydrocarbon wax using a vinyl monomer such as styrene or acrylic acid; partial esters between a polyhydric alcohol and a fatty acid such as behenine monoglyceride and hydroxylated methyl esters obtained by hydrogenation of vegetable oils.

A value of 60 to 140 ° C is preferred for the peak point temperature of the maximum endothermic peak during heating in the measurement of the release agent with a differential scanning calorimeter (DSC) for the melting point. 60 to 90 ° C is more preferred. A melting point of at least 60 ° C is preferable because it facilitates the adjustment in the fixing region for the magnetic toner of the present invention. On the other hand, a melting point of not more than 140 ° C is preferable because it facilitates an improvement in low-temperature fixability.

The content of this releasing agent, expressed in terms of 100 parts by mass of the binder resin, is preferably from 0.1 to 20 parts by mass, and more preferably from 0.5 to 10 parts by mass.

When the releasing agent content is at least 0.1 part by mass, the separation of the fixing coat is facilitated, and the cold impression property is easily improved. On the other hand, if the releasing agent content is not more than 20 parts by mass, the deterioration of the magnetic toner during the long-term use is inhibited and improved image stability is thereby facilitated.

The release agent may be in the binder resin z. Example, be introduced by methods in which during resin production, the resin is dissolved in a solvent, the temperature of the resin solution is raised and addition and mixing is carried out during stirring, or by processes in which the addition during the melt kneading during toner production takes place ,

The magnetic toner of the present invention contains inorganic fine particles on the surface of the magnetic toner particles.

The inorganic fine particles present on the surface of the magnetic toner particles may be exemplified by silica fine particles, titania fine particles and alumina fine particles, and these inorganic fine particles may also be advantageously used after performing a hydrophobic treatment on the surface thereof.

It is critical that the inorganic fine particles present on the surface of the magnetic toner particles in the present invention contain at least one type of metal oxide fine particles selected from the group consisting of silica fine particles, titania fine particles and alumina fine particles, and at least 85 mass% of the metal oxide fine particles are silica fine particles. Preferably, at least 90% by weight of the metal oxide fine particles are silica fine particles. The reasons are that Not only do silica fine particles provide the best balance in terms of charging performance and fluidity, but they are also excellent from the standpoint of reducing the aggregative forces between the toners.

The reason why silica fine particles are excellent from the standpoint of reducing the aggregative forces between the toners is not entirely clear, but it is hypothesized that this is presumably because of the essential mode of carrying out the previously described storage action on the sliding behavior between the silica fine particles.

In addition, silica fine particles are preferably the main constituent of the inorganic fine particles fixed on the surface of the magnetic toner particles. Specifically, the inorganic fine particles fixed on the surface of the magnetic toner particles preferably contain at least one type of metal oxide fine particles selected from the group consisting of silica fine particles, titania fine particles and alumina fine particles, wherein silica fine particles are at least 80 mass% of these metal oxide fine particles. The silica fine particles are more preferably at least 90 mass%. It is believed that this is for the same reason as discussed before: Silica fine particles are the best from the standpoint of imparting charge performance and flowability, and as a consequence, a rapid initial increase in the toner magnetic charge occurs. The result is that a high image density can be obtained, which is highly preferred.

Here, the adjustment of the timing and the amount of addition of the inorganic fine particles may be used to bring the silica fine particles to at least 85 mass% of the metal oxide fine particles present on the surface of the magnetic toner particle, and in the metal oxide particles fixed on the magnetic toner particle surface, the silica fine particles as well to bring at least 80% by mass.

The amount of the inorganic fine particles present can be checked using the methods for quantifying the inorganic fine particles described below.

The number average particle diameter (D1) of the primary particles in the inorganic fine particles in the present invention is preferably from at least 5 nm to not more than 50 nm, and more preferably from at least 10 nm to not more than 35 nm.

Bringing the number average particle diameter (D1) of the primary particles in the inorganic fine particles in the aforementioned range advantageously facilitates control of the coverage ratios A and B / A. When the number-average particle diameter (D1) of the primary particles is less than 5 nm, the inorganic fine particles tend to aggregate with each other, and it is not only difficult to obtain large B / A values, but the variation coefficient of the coverage ratio A also tends to be large Values. On the other hand, when the number-average particle diameter (D1) of the primary particles is larger than 50 nm, the coverage ratio A tends to be low even for large amounts of addition of the inorganic fine particles because the value for B / A also tends to be low. because the inorganic fine particles are difficult to fix to the magnetic toner particle. Consequently, it is difficult to obtain the above-described attachment force reducing effect and storage efficiency when the number average particle diameter (D1) of the primary particles is larger than 50 nm.

A hydrophobic treatment is preferably performed on the inorganic fine particles used in the present invention, and particularly preferred inorganic fine particles will be hydrophobically treated to have a hydrophobicity, as measured by the methanol titration test, of at least 40%, and more preferably at least 50%.

The method for carrying out the hydrophobic treatment can be exemplified by a method in which a treatment is carried out, e.g. Example, with an organic silicon compound, a silicone oil, a long-chain fatty acid, etc.

The organic silicon compounds can be exemplified by hexamethyldisilazane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane and hexamethyldisiloxane. A single one of these may be used, or a mixture of two or more may be used.

The silicone oil can be exemplified by dimethylsilicone oil, methylphenylsilicone oil, α-methylstyrene-modified silicone oil, chlorophenylsilicone oil and fluorine-modified silicone oil.

A C _10-22 fatty acid is suitably used for the long-chain fatty acid, and the long-chain fatty acid may be a straight-chain fatty acid or a branched fatty acid. A saturated fatty acid or an unsaturated fatty acid can be used.

Of the above, C _10-22 straight-chain saturated fatty acids are highly preferred because they readily provide a uniform treatment of the surface of the inorganic fine particles.

These straight-chain saturated fatty acids can be exemplified by capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid and behenic acid.

Inorganic fine particles treated with silicone oil are preferred for the inorganic fine particles used in the present invention, and inorganic fine particles treated with an organic silicon compound and a silicone oil are more preferable. This allows advantageous control of hydrophobicity.

The method of treating the inorganic fine particles with a silicone oil can be exemplified by a method in which the silicone oil is mixed directly with inorganic fine particles treated with an organic silicon compound using a mixer such as a Henschel mixer. and by a method in which the silicone oil is sprayed on the inorganic fine particles. Another example is a method in which the silicone oil is dissolved or dispersed in a suitable solvent; the inorganic fine particles are then added and mixed; and the solvent is removed.

In order to obtain a good hydrophobicity, the amount of the silicone oil used for the treatment, expressed per 100 parts by mass of the inorganic fine particles, is preferably from at least 1 part by mass to not more than 40 parts by mass, and more preferably from at least 3 parts by mass to not more than 35 parts by mass.

In order to impart excellent flowability to the magnetic toner, the silica fine particles, titanium oxide fine particles and alumina fine particles used by the present invention preferably have a specific surface area measured by BET method based on nitrogen adsorption (BET specific surface area) of at least 20 m ² / g to not more than 350 m ² / g, and more preferably from at least 25 m ² / g to not more than 300 m ² / g.

The specific surface area (BET specific surface area) measurement by the BET method based on the nitrogen adsorption is performed based on JIS Z8830 (2001). A "TriStar300 (Shimadzu Corporation) automatic specific surface area" pore distribution analyzer "which uses gas adsorption by a constant volume technique in its measurement procedure is used as the measuring instrument.

The addition amount of the inorganic fine particles expressed per 100 parts by mass of the magnetic toner particles is preferably from at least 1.5 parts by mass to not more than 3.0 parts by mass of the inorganic fine particles, more preferably from at least 1.5 parts by mass to not more than 2.6 parts by mass even more preferably from at least 1.8 parts by weight to not more than 2.6 parts by weight.

With the additional amount of inorganic fine particles set in the specified range, the coverage ratios A and B / A can be adequately controlled.

Exceeding 3.0 mass parts for the addition amount of the inorganic fine particles, even if an external addition device and an external addition method could be invented, results in an increase in the release of the inorganic fine particles and facilitates the occurrence of, e.g. B., a strip in the picture.

In addition to the above-described inorganic fine particles, particles having a primary number average particle diameter (D1) of at least 80 nm to not more than 3 μm may be added to the magnetic toner of the present invention. For example, a lubricant, e.g. A fluororesin powder, zinc stearate powder or polyvinylidene fluoride powder; a polish, e.g. A ceria powder, a silicon carbide powder or a strontium titanate powder; or a spacer particle such as silica may be added in small amounts that do not affect the effects of the present invention.

From the viewpoint of the balance between the development performance and the fixing performance, the weight-average particle diameter (D4) of the magnetic toner of the present invention is preferably at least 6.0 μm to not more than 10.0 μm, and more preferably from at least 7.0 μm to not more than 9.0 μm.

In addition, as viewed from the point of view of suppression of excessive charge, the average circularity of the magnetic toner of the present invention is preferably from at least 0.935 to not more than 0.955, and more preferably from at least 0.938 to not more than 0.950.

The average roundness of the magnetic toner of the present invention can be adjusted in the specified range by adjusting the method for producing the magnetic toner and adjusting the production conditions.

Examples of the method for producing the magnetic toner of the present invention will be provided below, but there is no intention to limit the manufacturing method to them.

The magnetic toner of the present invention can be produced by any known method which enables adjustment of the coverage ratio A and B / A, which preferably has a step in which the average roundness can be adjusted while the other manufacturing steps are not particularly limited.

The following method is an advantageous example of such a manufacturing method. First, the binder resin and the magnetic body and, if necessary, other raw materials, e.g. For example, a release agent and a charge control agent are mixed extensively using a mixer such as a Henschel mixer or a ball mill, and then melted, processed and kneaded using a heated kneader such as a roller, kneader, or extruder to remove the To compatibilize resins.

The obtained molten and kneaded material is cooled and solidified and then coarsely pulverized, finely pulverized and classified, and the external additives, e.g. For example, inorganic fine particles are externally added to the resulting magnetic toner particles and mixed to obtain the magnetic toner.

The mixer used herein may be exemplified by the Henschel mixer (Mitsui Mining Co., Ltd.); the super mixer (Kawata Mfg. Co., Ltd.); Ribocone (Okawara Corporation); Nauta Mixer, Turbulizer and Cyclomix, Nobilta (Hosokawa Micron Corporation); Spiral Pin Mixer (Pacific Machinery & Engineering Co., Ltd.); and Loedige Mixer (Matsubo Corporation).

The aforementioned kneader can be exemplified by KRC Kneader (Kurimoto, Ltd.); Buss Ko-Kneader (Buss Corp.); TEM extruder (Toshiba Machine Co., Ltd.); TEX Twin Screw Kneader (The Japan Steel Works, Ltd.); PCM Kneader (Ikegai Ironworks Corporation); Three-roll mills, mixing roll mills, kneaders (Inoue Manufacturing Co., Ltd.); Kneadex (Mitsui Mining Co., Ltd.); Model MS Pressure Kneader and Kneader Rudder (Moriyama Mfg. Co., Ltd.); and Banbury Mixer (Kobe Steel, Ltd.).

The aforementioned pulverizers can be exemplified by Counter Jet Mill, Micron Jet, and Inomizer (Hosokawa Micron Corporation); IDS mill and PJM Jet Mill (Nippon Pneumatic Mfg. Co., Ltd.); Cross Jet Mill (Kurimoto, Ltd.); Ulmax (Nisso Engineering Co., Ltd.); SK Jet-O-Mill (Seishin Enterprise Co., Ltd.); Kryptron (Kawasaki Heavy Industries, Ltd.); Turbo Mill (Turbo Kogyo Co., Ltd.); and Super Rotor (Nisshin Engineering Inc.).

From the foregoing, the average roundness can be controlled by adjusting the exhaust gas temperature during micropulverization using a turbo-mill. A lower exhaust gas temperature (eg, not more than 40 ° C) provides a lower value for the average roundness, while a higher exhaust gas temperature (eg, about 50 ° C) provides a higher value for the average circularity.

The aforementioned classifier can be exemplified by the Classiel, Micron Classifier, and Spedic Classifier (Seishin Enterprise Co., Ltd.); Turbo Classifier (Nisshin Engineering Inc.); Micron Separator, Turboplex (ATP) and TSP Separator (Hosokawa Micron Corporation); Elbow Jet (Nittetsu Mining Co., Ltd.); Dispersion Separator (Nippon Pneumatic Mfg. Co., Ltd.); and YM Microcut (Yasukawa Shoji Co., Ltd.).

Screening devices that can be used to screen the coarse particles can be exemplified by Ultrasonic (Koei Sangyo Co., Ltd.), Rezona Sieve and Gyro-Sifter (Tokuju Corporation), Vibrasonic System (Dalton Co., Ltd .), Soniclean (Sintokogio, Ltd.), Turbo Screener (Turbo Kogyo Co., Ltd.), Microsifter (Makino Mfg. Co., Ltd.), and circular vibrating sieves.

A known Mischverfahrengerät, z. The mixers described above, can be used for the external addition and mixing of the inorganic fine particles; however, one is in the 4 shown device from the standpoint of enabling easy control of the coverage ratio A, B / A and the coefficient of variation on the coverage ratio preferred.

The 4 Fig. 10 is a schematic diagram showing an example of a mixing process apparatus which can be used to carry out the external addition and mixing of the inorganic fine particles used by the present invention.

This mixing process apparatus immediately gives the fixation of the inorganic fine particles on the surface of the magnetic toner particle because it has a structure that exerts shear forces in a narrow workspace area on the magnetic toner particles and the inorganic fine particles.

Further, as described below, the coverage ratio A, B / A and the coefficient of variation on the coverage ratio A are easily controlled in the ranges preferred for the present invention because the circulation of the magnetic toner particles and inorganic fine particles in the axial direction of the rotary member facilitates and because an extensive and even mixture is facilitated before the development of fixation.

On the other hand, that is 5 Fig. 10 is a schematic diagram showing an example of the structure of the stirring member used in the aforementioned mixing processing apparatus.

The method for external addition and mixing for the inorganic fine particles will be described below using the 4 and 5 described.

This mixing process apparatus, which performs external addition and mixing of the inorganic fine particles, has a rotary member 2 on, wherein on the surface thereof at least a plurality of stirring members 3 are arranged; a drive component 8th which drives the rotation of the rotating member; and a main body 1 , which is arranged so that there is a gap with the stirring members 3 having.

It is important that the gap (working space) between the inner circumference of the main body 1 and the stirring member 3 is kept constant and very small to exert a uniform shearing force on the magnetic toner particles and to facilitate the fixation of the inorganic fine particles on the surface of the magnetic toner particle.

The diameter of the inner circumference of the main body 1 in this device is not more than 2 times the diameter of the outer circumference of the rotating component 2 , In 4 an example is shown in which the diameter of the inner circumference of the main housing 1 1.7 times the diameter of the outer circumference of the rotating component 2 is (the trunk diameter provided by subtracting the stirring member 3 from the rotating component 2 ). If the diameter of the inner circumference of the main body 1 more than 2 times the diameter of the outer periphery of the rotating member 2 is the driving force on the magnetic toner particles satisfactorily exerted because the processing space in which the forces act on the magnetic toner particles is suitably limited.

In addition, it is important that the aforementioned work space be adjusted in accordance with the size of the main body. From the viewpoint of applying adequate gravity to the magnetic toner particles, it is important that the working space be adjusted from about at least 1% to not more than 5% of the diameter of the inner circumference of the main body. Specifically, when the diameter of the inner periphery of the main body 1 is about 130 mm, the working space is preferable adjusted from at least 2 mm to not more than 5 mm; When the diameter of the inner periphery of the main body 1 is about 800 mm, the working space is preferably set from about at least 10 mm to not more than 30 mm.

In the method of externally adding and mixing the inorganic fine particles in the present invention, mixing and externally adding the inorganic fine particles to the surface of the magnetic toner particle by using the mixing processing apparatus by rotating the rotating member 2 through the drive component 8th and stirring and mixing the magnetic toner particles and inorganic particles introduced into the mixing process apparatus.

Like in the 5 at least a portion of the plurality of stirring members is shown 3 as a forward transporting stirring member 3a formed, accompanying the rotation of the rotating component 2 the magnetic toner particles and inorganic fine particles are transported in a direction along the axial direction of the rotary member. In addition, at least part of the plurality of stirring members becomes 3 as a return transporting member 3b formed, which is the rotation of the rotating component 2 accompanying, the magnetic toner particles and inorganic fine particles in the other direction along the axial direction of the rotating member returns.

Here, when the raw material inlet port 5 and the product delivery port 6 at the two ends of the main body 1 are arranged as in the 4 , the direction of the product delivery opening 6 from the raw material inlet port 5 (the direction to the right in the 4 ) the "forward direction".

That means, like in the 5 is shown, the area of the Vorwärtstransportrührbauteils 3a inclined to move the magnetic toner particles in the forward direction ( 13 ) to transport. On the other hand, the surface of the Rücktransportrühbauteils 3b inclined to move the magnetic toner particles and the inorganic fine particles in the reverse direction (FIG. 12 ) to transport.

Thereby, external addition of the inorganic fine particles to the surface of the magnetic toner particles and mixing are performed while repeatedly transporting in the "forward direction" (FIG. 13 ) and a transport in the "backward direction" ( 12 ) is carried out.

Additionally is overlooking the stirring components 3a . 3b Forming a plurality of components arranged at intervals in the circumferential direction of the rotating member 2 a set. In the in the 5 shown example, two components form a set of the stirring components at a distance of 180 ° with each other 3a . 3b on the rotating component 2 but a larger number of components may form one set, such as three at an interval of 120 ° or four at an interval of 90 °.

In the in the 5 Example shown is a total of twelve stirring components 3a . 3b formed in an equal interval.

Furthermore, D in 5 the width of a stirring member and d indicates the distance indicating the overlapping portion of a stirring member. In 5 D is preferably a width of from at least about 20% to not more than 30% of the length of the rotating component 2 is from the standpoint of providing efficient transport of the magnetic toner particles and inorganic fine particles in the forward direction and the reverse direction. 5 shows an example in which D is 23%. Furthermore, with a view to the stirring components 3a and 3b when a Maßhilfslinie in the right-angle direction of the arrangement of the end of the stirring member 3a is drawn, is a certain overlapping area d of the stirring member with the stirring member 3b preferably present. This serves to efficiently apply shear forces to the magnetic toner particles. This d is preferably at least 10% to not more than 30% of D from the viewpoint of exerting shear forces.

In addition to the in 5 As shown, the blade shape - as the magnetic toner particles can be transported in the forward and backward direction and the working space is maintained - may be a shape having a curved surface or a paddle structure in which a distal to the rotating member 2 is connected by a rod-shaped arm.

The present invention will hereinafter be described in additional detail with reference to the schematic diagrams of FIGS 4 and 5 explained devices explained.

This in 4 shown device has a rotating component 2 having at least a plurality of stirring members disposed on its surface; a drive component 8th that the rotation of the rotating component 2 drives; a main body 1 , which is arranged to form a gap with the stirring members 3 to build; and a coat 4 in which a heat transfer medium can flow and which on the inside of the main housing 1 and on the end surface 10 of the rotating component is located.

In addition, this points in the 4 shown apparatus has a raw material inlet opening 5 on, on the upper side of the main body 1 for the purpose of introducing the magnetic toner particles and the inorganic fine particles, and a product discharge port 6 , which are on the lower side of the main body 1 for the purpose of discharging the magnetic toner subjected to the external addition and mixing process from the main body 1 outward.

That in the 4 The apparatus shown also has a raw material inlet opening inside piece 16 in the starting material inlet opening 5 is inserted, and a Produktauslassöffinneninnenstück 17 that in the product outlet 6 is inserted.

In the present invention, the raw material inlet port inner piece becomes 16 first from the raw material inlet port 5 removed, and the magnetic toner particles are in the processing rooms 9 from the raw material inlet port 5 introduced. Then, the inorganic fine particles are introduced into the processing space from the raw material inlet port 5 introduced, and the raw material inlet opening inner piece 16 is inserted. The rotating component 2 is subsequently by the drive component 8th rotates ( 11 represents the direction of rotation) and the material to be processed thereby is subjected to the external addition and mixing process while being stirred and mixed by the plurality of stirring members 3 on the surface of the rotating component 2 are arranged.

The sequence of introduction may also include introduction of the inorganic fine particles through the raw material inlet port 5 and then introducing the magnetic toner particles through the raw material inlet port 5 be. In addition, the magnetic toner particles and the inorganic fine particles may be previously mixed using a mixer such as a Henschel mixer, and thereafter the mixture may pass through the raw material inlet port 5 in the 4 introduced device can be introduced.

More specifically, in view of the conditions of the external addition and mixing process, the control of the power of the driving member is 8th from at least 0.2 W / g to not more than 2.0 W / g, preferably in terms of obtaining the coverage ratio A, B / A and the coefficient of variation on the coverage ratio A as specified in the present invention. The control of the power of the drive member to from at least 0.6 W / g to not more than 1.6 W / g is more preferable.

If the power is less than 0.2 W / g, it is difficult to obtain a high coverage ratio A, and B / A tends to be too low. On the other hand, B / A tends to be too high when 2.0 W / g is exceeded.

The processing time is not particularly limited, but is preferably from at least 3 minutes to not more than 10 minutes. If the processing time is less than 3 minutes, B / A tends to be too low and a large coefficient on the coverage ratio A is prone to occur. On the other hand, if the processing time exceeds 10 minutes, conversely, B / A tends to be too high, and the temperature inside the apparatus is liable to increase.

The rotational speed of the stirring members during external addition and mixing is not particularly limited; however, if, for that in the 4 Device shown, the volume of the processing room 9 in the apparatus is 2.0 × 10 ^-3 m ³ , is the rpm for the stirring members - if the shape of the stirring members 3 like in the 5 is shown - preferably from at least 1000 U / min to not more than 3000 U / min. The coverage ratio A, B / A and the coefficient of variation on the coverage ratio A as specified in the present invention are easily obtained at at least 1000 rpm to not more than 3000 rpm.

A particularly preferred processing method of the present invention comprises a premixing step prior to the external addition and mixing step. The incorporation of a premixing step achieves a very uniform dispersion of the inorganic fine particles on the surface of the magnetic toner particle, and as a result, a high coverage ratio A is easily obtained and the coefficient of variation on the coverage ratio A is easily reduced.

More specifically, the premix processing conditions are preferably power of the drive member 8th from at least 0.06 W / g to not more than 0.20 W / g and a working time of at least 0.5 minutes to not more than 1.5 minutes. It is difficult to obtain a satisfactory uniform mixture in the premixing when the charged power is higher than 0.20 W / g or the processing time is longer than 1.5 minutes for the premix processing conditions, the inorganic fine particles may be fixed on the surface of the magnetic toner particle before a satisfactory even mixture is achieved.

After the external addition and mixing operation has been completed, the product discharge port inner becomes 17 in the product delivery opening 6 removed and the rotating component 2 is by the drive component 8th rotates to remove the magnetic toner from the product discharge port 6 leave. If necessary, coarse particles, etc., may be obtained from the obtained magnetic toner using a sorter or a screen, e.g. A circular vibrating sorter to remove the magnetic toner.

An example of an image forming apparatus which can advantageously use the toner of the present invention will be described specifically below with reference to FIGS 3 described. In the 3 is 100 an electrostatic latent image bearing member (hereinafter also referred to as a photosensitive member), and the following are arranged, among others, on its periphery: a charge member (charge roller) 117 , a development device 140 with a toner-carrying component 102 , a transfer member (transfer charge roller) 114 , a cleaner container 116 , a fuser unit 126 and a pickup roller 124 , The electrostatic latent image bearing member 100 is with the charging roller 117 loaded. Light exposure is performed by irradiating the electrostatic latent image bearing member 100 with laser light from a laser generator 121 to form an electrostatic latent image corresponding to the intended image. The electrostatic latent image on the electrostatic latent image bearing member 100 is through the development device 140 developed with a monocomponent toner to form a toner image, and the toner image is transferred onto a transfer material through the transfer roller 114 which contacts an electrostatic latent image bearing member with the transfer material interposed therebetween. A toner image carrying transfer material becomes the fixing unit 126 conveyed, and fixing on the transfer material is performed. In addition, the toner remaining on the electrostatic latent image bearing member is scraped by the cleaning blade and stored in the cleaner container 116 added.

The methods for measuring the various properties relating to the present invention will be described below.

<Quantitative method for inorganic fine particles>

(1) Determination of Content of Silica Fine Particles in Magnetic Toner (Standard Addition Method)

3 g of the magnetic toner is placed in an aluminum ring with a diameter of 30 mm and a compact is prepared under a pressure of 10 tons. The silicon (Si) density is determined (Si density-1) by wavelength dispersive X-ray fluorescence analysis (XRF). The measurement conditions are preferably optimized for the XRF instrument used and all intensity measurements in a row are performed using the same conditions. Silica fine particles having a number-average particle diameter of the primary particles of 12 nm are added to the magnetic toner at 1.0 mass% with respect to the magnetic toners, and mixing is carried out with a coffee grinder.

For the silica fine particles mixed at this time, silica fine particles having a number average particle diameter of the primary particles of about 5 nm to not more than 50 nm can be used without adversely affecting this determination.

After mixing, a pelletization as described above is performed, and the Si intensity (Si intensity-2) is also determined as previously described. Using the same procedure, the Si intensity (Si intensity-3, Si intensity-4) for samples prepared by adding and mixing the silica fine particles is also referred to 2.0 mass% and 3.0 mass% of the silica fine particles determined on the magnetic toner. The silica content (mass%) in the magnetic toner based on the standard addition method is calculated using the Si intensities-1 to -4.

The titanium oxide content (mass%) in the magnetic toner and the alumina content (mass%) in the magnetic toner are determined using the standard addition method and the same procedure as previously described for the determination of the silica content. That is, for the titania content (mass%), titania fine particles having a number average particle diameter of primary particles of at least 5 nm to not more than 50 nm are added and mixed, and the determination can be made by determining the titanium (Ti) intensity. For the alumina content (mass%), alumina fine particles having a number-average particle diameter of primary particles of at least 5 nm to not more than 50 nm are added and mixed, and the determination can be made by determining the aluminum (Al) intensity.

(2) Separation of the inorganic fine particles from the magnetic toner

5 g of the magnetic toner is weighed using a precision balance into a 200-mL plastic cup with lid; 100 mL of methanol is added and dispersion is carried out for 5 minutes using an ultrasonic dispersion device. The magnetic toner is held using a neodymium magnet and the supernatant is discarded. The process of dispersion with methanol and discarding the supernatant is performed three times, followed by the addition of 100 mL of 10% NaOH and several drops of "Contaminon N" (a 10% by weight aqueous solution of neutral pH 7 detergent for the purification of Precision measuring instruments and a non-ionic surfactant, an anionic surfactant, and an organic builder, from Wako Pure Chemical Industries, Ltd., comprising), mix gently and then let stand for 24 hours. This is followed by re-separation using a neodymium magnet. At this time, repeated washing with distilled water is performed until no NaOH remains. The recovered particles are extensively dried using a vacuum dryer to obtain Particle A. The externally added silica fine particles are dissolved and removed by this method. Titanium oxide fine particles and fine alumina particles may remain in the particles A since they are sparingly soluble in 10% NaOH.

(3) Measurement of Si intensity in particles A

3 g of the particles A are introduced into an aluminum ring with a diameter of 30 mm; a compact is produced using a pressure of 10 tons; and the Si intensity (Si intensity-5) is determined by wavelength-dispersive XRF. The silica content (mass%) in the particles A is calculated using the Si intensity-5 and the Si intensities-1 to -4 used in the determination of the silicon content in the magnetic toner.

(4) Separation of the magnetic body from the magnetic toner

100 ml of tetrahydrofuran is added to 5 g of Particles A with extensive mixing followed by ultrasonic dispersion for 10 minutes. The magnetic body is held with a magnet and the supernatant is discarded. This process is carried out 5 times to obtain Particle B. This process can almost completely replace the organic component, e.g. As resins, outside the magnetic body. However, because a tetrahydrofuran-insoluble material may remain in the resin, the particles B provided by this method are preferably heated to 800 ° C to burn out the residual organic component, and the particles C obtained after heating are approximately the magnetic body. which was present in the magnetic toner.

Measurement of the mass of the particles C gives the content of magnetic bodies W (mass%) in the magnetic toner. In order to correct the increase due to the oxidation of the magnetic body, the mass of the particles C is multiplied by 0.9666 (Fe ₂ O ₃ → Fe ₃ O ₄ ).

(5) Measurement of Ti intensity and Al intensity in the separated magnetic body

Ti and Al may be present as impurities or additives in the magnetic body. The amount of Ti and Al attributable to the magnetic body can be detected by FP quantification in the wavelength-dispersive XRF. The detected amounts of Ti and Al are converted to titania and alumina, and the titania content and alumina content in the magnetic body are then calculated.

The amount of externally added silica fine particles, the amount of externally added titania fine particles, and the amount of externally added alumina fine particles are carried out Substituting the quantitative values obtained by the foregoing procedures in the following formulas. Amount of externally added silica fine particles (% by mass) = Silica content (% by mass) in the magnetic toner - Silicon content (% by mass) in Particles A. Amount of externally added titanium oxide fine particles (mass%) = titanium oxide content (mass%) in the magnetic toner - {titanium oxide content (% by mass) in the magnetic body × magnetic body content W / 100} Amount of externally added alumina fine particles (mass%) = alumina content (mass%) in the magnetic toner - {alumina content (mass%) in the magnetic body × magnetic body content W / 100}

(6) Calculation of the content of silica fine particles in the metal oxide fine particles selected from the group consisting of silica fine particles, titania fine particles, and alumina fine particles for the inorganic fine particles fixed to the magnetic toner particle surface

After carrying out the procedure of "removing the unfixed inorganic fine particles" in the method for calculating the coverage ratio B as described below and then drying the toner, the proportion of the silica fine particles in the metal oxide fine particles can be determined by carrying out the whole procedure as in the previously described methods of (1) to (5).

<Method for the measurement of the number-average particle diameter of primary particles of inorganic fine particles>

The number-average particle diameter of the primary particles of the inorganic fine particles is calculated from the image of inorganic fine particles on the magnetic toner surface recorded by Hitachi S-4800 ultra-high resolution field emission scanning electron microscopy (Hitachi High-Technologies Corporation). The conditions for image acquisition with the S-4800 are as follows.

The same steps (1) to (3) as previously described in "calculation of the coverage ratio A" are performed; Focusing is performed by performing focus adjustment on a 50000X (50k) magnification of the magnetic toner surface as in (4); and the brightness is then adjusted using the ABC mode. This is followed by bringing the magnification to 100000X (100k); Performing the focus adjustment using the focus knob and the STIGMA / ALIGNMENT knobs as in (4); and focusing using the autofocus. The focus adjustment operation is repeated to achieve focus at 100000X (100k).

Thereafter, the particle diameter of at least 300 inorganic fine particles on the magnetic toner surface is measured, and the number average particle diameter (D1) is determined. Here, since the inorganic fine particles are also present as aggregates, the maximum diameter is determined based on what can be identified as the primary particle, and the number average particle diameter of the primary particles (D1) is obtained by taking the arithmetic mean of the obtained maximum diameters.

<Calculation of the coverage ratio A>

In the present invention, the coverage ratio A is analyzed by analyzing using an Image-Pro Plus ver. 5.0 image analysis software (Nippon Roper Kabushiki Kaisha) wherein the magnetic toner surface image is taken with Hitachi's S-4800 ultra high resolution field emission scanning electron microscope (Hitachi High-Technologies Corporation ). The conditions for image acquisition with the S-4800 are as follows.

(1) Sample preparation

An electroconductive paste is spread in a thin layer on the sample holder (15 mm x 6 mm aluminum sample holder) and the magnetic toner is sprayed thereon. Additional blowing with air is performed to remove excess magnetic toner from the sample holder and to perform thorough drying. The sample holder is inserted into the sample holder and the sample holder height is set to 36 mm with the sample height indicator.

(2) Setting conditions for viewing with the S-4800

Coverage ratio A is calculated using the image obtained by backscattering electron imaging with the S-4800. The coverage ratio can be measured with excellent accuracy using the backscattered electron image because the inorganic fine particles are less over-charged than in the case of the secondary electron image.

Introducing liquid nitrogen up to the top edge of the anti-contamination case placed in the S-4800 housing and allowing to stand for 30 minutes. Start the S-4800's "PC-SEM" and flashing (the FE tip, which is the electron source, is cleaned). Press the acceleration voltage display area in the control bar on the screen and press the [Blink] button to open the flashing execution dialog. Confirming a flashing intensity of 2 and execution. Confirm that the emission due to blinking is 20 to 40 μA. Insert the sample holder into the sample chamber of the S-4800 housing. Press [home] on the control bar to transfer the sample retention device to the observation position.

Press the acceleration voltage display area to open the HV setting dialog and set the acceleration voltage to [0.8 kV] and the emission current to [20 μA]. In the [base] tab on the control panel, set the signal selection to [SE]; Selecting [upper (U)] and [+ BSE] for the SE detector; and selecting [L. A. 100] in the selection box to the right of [+ BSE] to enter the viewing mode using the backscattered electron image. Similarly, in the [base] tab of the operation panel, the probe current of the electronic optical system operation block is set to [Normal]; the focus mode is set to [CLOCK]; and WD set to [3.0 mm]. Press the [ON] button in the accelerator voltage of the control panel and apply the accelerating voltage.

(3) Calculation of the number-average particle diameter (D1) of the magnetic toner

Adjust the magnification to 5000X (5k) by dragging the magnification display area of the control panel. Turning the [COARSE] focus knob on the control panel and adjusting the aperture balance where some image clarity has been obtained. [Align] in the control panel and display the calibration dialog and select [beam]. Drag the displayed beam to the center of the concentric circles by turning the STIGMA / ALIGNMENT knobs (X, Y) on the control panel. Then selecting [aperture] and turning the STIGMA / ALIGNMENT knobs (X, Y) one by one and adjusting so as to stop the movement of the image or to minimize the movement. Close the aperture dialog and focus with the autofocus. Focus by repeating this process for an additional two times.

Then, determine the number-average particle diameter (D1) by measuring the particle diameter at 300 magnetic toner particles. The particle diameter of the single particle is taken as the maximum diameter when the magnetic toner particle is observed.

(4) focus adjustment

For particles with a number-average particle diameter (D1) obtained in (3) of ± 0.1 μm with the center point of the maximum diameter. set to the center of the screen, drag the magnification display area of the control panel to set the magnification to 10000X (10k). Turn the [COARSE] focus knob on the control panel and adjust the aperture setting where some levels of sharpness have been achieved. Press [Align] on the control panel and display the calibration dialog and select [beam]. Extend the displayed beam to the center of the concentric circles by rotating the STIGMA / ALIGNMENT knobs (X, Y) on the control panel. Then selecting [aperture] and turning the STIGMA / ALIGNMENT knobs (X, Y) one at a time and adjusting to stop the movement of the image or to minimize the movement. Close the aperture dialog and focus using the autofocus. Then set the magnification to 50000X (50k); Performing the focus adjustment as before using the focus knob and the STIGMA / ALIGNMENT knob; and then refocus using the autofocus. Focus by repeating this process. Here, because the accuracy of Cover ratio measurement prone to diminish, if the viewing plane has a large tilt angle, the analysis is made by a selection with the least tilt in the surface by making a selection during focus adjustment, in which the entire viewing plane is simultaneously in focus.

(5) image capture

Performing brightness adjustment using the ABC mode and taking a photograph of 640 × 480 pixels and storing. Perform the analysis described below using this image file. Take a shot for each magnetic toner particle and obtain images for at least 30 magnetic toner particles.

(6) image analysis

The coverage ratio A is obtained in the present invention by using the analysis software mentioned below by subjecting the obtained image to the above-described procedure for binarization processing. When this is done, the previously described frame is divided into 12 squares and each is analyzed. However, if an inorganic fine particle having a particle diameter larger than or equal to 50 nm is present in a partial area, the calculation of the coverage ratio A for this partial area is not performed.

The analysis conditions with the Image-Pro Plus ver. 5.0 image analysis software are as follows:
Software: Image-ProPlus5.1J

From "measurement" in the toolbar, select "count / size" and then "option" and set the binarization conditions. Selecting 8 references in the object extraction option and setting the smoothing to 0. Additionally, preliminary sorting, filling in blanks and envelopes are not selected and the "exclusion of boundary line" is set to "none". Select "measurement items" from "measurement" in the toolbar and enter 2 to 10 for the area scan area.

The coverage rate is calculated by plotting a square zone. Here, the area (C) is set to 24000 to 26000 pixels. Automatic binarization is performed by "processing" binarization and the total area (D) of the silica-free zone is calculated.

The coverage ratio a is calculated using the following formula from the area C of the square zone and the total area D of the silica-free zone. Coverage Ratio a (%) = 100 - (D / C × 100)

As previously mentioned, the calculation of the coverage ratio a is performed for at least 30 magnetic toner particles. The average value of all data obtained is taken as the coverage ratio A of the present invention.

<Variation coefficient on the coverage ratio A>

The coefficient of variation on the coverage ratio A is determined in the following invention as follows. The coefficient of variation on the coverage ratio A is obtained by the following formula when σ (A) is the standard deviation of all coverage ratio data used in the coverage ratio A calculation described above. Coefficient of variation (%) = {σ (A) / A} × 100

<Calculation of the coverage ratio B>

The coverage ratio B is first removed by removing the unfixed inorganic fine particles on the magnetic toner surface and then performing the same procedure as that followed in the calculation of the coverage ratio A.

(1) Removal of unfixed inorganic fine particles

The unfixed inorganic fine particles are removed as described below. The inventors examined and then adjusted these removal conditions to thoroughly remove the inorganic fine particles other than those embedded in the toner surface.

As an example, the 6 the relationship between the ultrasonic dispersion time and the magnetic toner coverage ratio calculated after ultrasonic dispersion, in which the coverage ratio A is 46% using the apparatus in the 4 was brought at three different external Zugabeintensitäten. The 7 was prepared by calculating the coverage ratio of a magnetic toner by removing the inorganic fine particles by ultrasonic dispersion by the method described below and then drying, using the same procedure as previously described for the calculation of the coverage ratio A.

The 6 shows that the coverage ratio decreases along with the removal of the inorganic fine particles by ultrasonic dispersion, and that for all external addition intensities, the coverage rate is brought to an approximately constant value by ultrasonic dispersion for 20 minutes. On this basis, ultrasonic dispersion for 30 minutes was considered to provide thorough removal of the other fine particles than the inorganic fine particles embedded in the toner surface, and the coverage rate thereby obtained was defined as the coverage ratio B.

More specifically, 16.0 g of water and 4.0 g of Contaminon N (a neutral detergent from Wako Pure Chemical Industries, Ltd., Product No. 037-10361) were placed in a 30 ml glass vial and mixed thoroughly. 1.50 g of the magnetic toner is introduced into the resulting solution and the magnetic toner is completely immersed by applying a magnet to the bottom. Thereafter, the magnet is moved around to condition the magnetic toner to the solution and to remove air bubbles.

The tip of a UH-50 ultrasonic oscillator (manufactured by SMT Co., Ltd., the tip used is a titanium alloy tip having a tip diameter of 0 6 mm) is inserted so that it is in the center of the vial and 5 mm above the bottom of the vial Vial is taken, and the inorganic fine particles are removed by ultrasonic dispersion. After applying ultrasound for 30 minutes, the total amount of the magnetic toner is removed and dried. During this time as little heat as possible is supplied, while a vacuum drying is carried out at not more than 30 ° C.

(2) Calculation of the coverage ratio B

After drying as described above, the coverage ratio of the magnetic toner is calculated for the above-described coverage rate A to obtain the coverage ratio B.

<Method for the measurement of the weight average particle diameter (D4) and the particle size distribution of the magnetic toner>

The weight average particle diameter (D4) of the magnetic toner is calculated as follows. The measuring instrument used is a "Coulter Counter Multisizer 3" (registered trademark, by Beckman Coulter, Inc.), a precision particle size distribution measuring instrument based on the pore electrical resistance principle and equipped with a 100 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying associated software, i. H. "Beckman Coulter Multisizer 3 Version 3.51" (from Beckman Coulter, Inc.). The measurements were carried out at 25000 channels for the number of effective measuring channels.

The aqueous electrolyte solution used for the measurements is prepared by dissolving a particularly pure sodium chloride in ion-exchanged water to provide a concentration of about 1 mass%, and e.g. For example, "ISOTON II" (from Beckman Coulter, Inc.) may be used.

The associated software is configured as follows before measurement and analysis.

In the "modify the standard operating method (SOM)" screen in the associated software, the total number of counts in the control mode is set to 50,000 particles; the number of measurements is set at once; and the Kd value is adjusted to the value using "standard particle 10.0 μm" (from Beckman Coulter, Inc.).

The threshold and noise level are set automatically by pressing the "threshold value / noise level measurement button". In addition, the current is set to 1600 μA, the amplitude ratio is set to 2; and the electrolyte is adjusted to ISOTON II; and a check is entered for the post-measurement aperture tube flush.

In the "setting conversion from pulses to particle diameter" screen of the associated software, the bin spacing (bin interval) is set to a logarithmic particle diameter; the particle diameter container is set to 256 particle diameter containers; and the particle diameter range is set from 2 μm to 60 μm.

• (1) Etwa 200 mL der vorher beschriebenen wässrigen Elektrolytlösung wird in einen für die Verwendung mit dem Multisizer 3 bestimmten 250 mL Rundbodenglasbecher gegeben und dieser wird in den Probenständer platziert und Rühren mit dem Rührstab gegen den Uhrzeigersinn wird bei 24 Umdrehungen pro Sekunde durchgeführt. Kontamination und Luftblasen innerhalb der Aperturröhre wurden vorher durch die „aperture flush”-Funktion der zugehörigen Software entfernt.
• (2) Etwa 30 mL der vorher beschriebenen wässrigen Elektrolytlösung wird in einen 100 mL Flachbodenglasbecher eingeführt. Zu diesem wird als Dispersionsmittel etwa 0,3 mL der durch die etwa dreifache (Masse) Verdünnung mit ionenausgetauschtem Wasser zubereitete Verdünnung von „Contaminon N” gegeben (eine 10 Masse-% wässrige Lösung eines Detergens mit neutralem pH 7 für die Reinigung von Präzisionsmessinstrumenten mit einem nicht ionischen Tensid, einem anionischen Tensid und einem organischen Gerüstbildner von Wako Pure Chemical Industries, Ltd.).
• (3) Ein „Ultrasonic Dispersion System Tetora 150” (Nikkaki Bios Co., Ltd.) wird vorbereitet. Dies ist eine Ultraschalldispersionsvorrichtung mit einer elektrischen Ausgabe von 120 W und ist mit zwei Oszillatoren (Oszillationsfregzenz = 50 kHz) ausgestattet, die derartig angeordnet sind, dass die Phasen um 180° verschoben sind. Etwa 3,3 L von ionenausgetauschtem Wasser wird in den Wassertank dieser Ultraschalldispersionsvorrichtung eingeführt und etwa 2 mL Contaminon N wird zu dem Wassertank gegeben.
• (4) Der in (2) beschriebene Becher wird in der Becherhalteröffnung der Ultraschalldispersionsvorrichtung gesetzt und die Ultraschalldispersionsvorrichtung wird gestartet. Die Höhe des Bechers wird in einer Art und Weise eingestellt, dass die Resonanzbedingung der Oberfläche der wässrigen Elektrolytlösung in dem Becher bei einem Maximum ist.
• (5) Während die wässrige Elektrolytlösung in dem eingesetzten Becher gemäß (4) mit Ultraschall beschallt wird, werden etwa 10 mg des Toners zu der wässrigen Elektrolytlösung in kleinen Aliquots zugegeben und die Dispersion wird durchgeführt. Die Ultraschalldispersionsbehandlung wird für zusätzliche 60 Sekunden fortgesetzt. Die Wassertemperatur in dem Wasserbad wird in geeigneter Weise während der Ultraschalldispersion gesteuert, um wenigstens 10°C und nicht mehr als 40°C zu sein.
• (6) Unter Verwendung einer Pipette wird die in (5) zubereitete dispergierte tonerhaltige Elektrolytlösung in den Rundbodenbecher eingesetzt in den wie in (1) beschriebenen Bodenständer mit Einstellung getröpfelt, um eine Messkonzentration von etwa 5% bereitzustellen. Die Messung wird dann durchgeführt bis die Anzahl der gemessenen Teilchen 50000 erreicht.
• (7) Die Messdaten werden durch die vorher zitierte mit dem Instrument zur Verfügung gestellte Software analysiert und der gewichtsbezogene mittlere Teilchendurchmesser (D4) wird berechnet. Bei Einstellung auf Grad/Volumen-% mit der zugehörigen Software, ist der „average diameter” auf dem „analysis/volumetric statistical value(arithmetic average)”-Bildschirm der gewichtsbezogene mittlere Teilchendurchmesser (D4).

The specific measuring procedure is as follows.

• (1) Place about 200 mL of the previously described aqueous electrolyte solution in a 250 mL round bottom glass beaker intended for use with the Multisizer 3 and place it in the sample rack and stir with the stir bar counterclockwise at 24 revolutions per second. Contamination and air bubbles within the aperture tube were previously removed by the "aperture flush" feature of the associated software.
• (2) Approximately 30 mL of the previously described aqueous electrolyte solution is introduced into a 100 mL flat-bottomed glass beaker. To this is added as the dispersing agent about 0.3 mL of the dilution of "Contaminon N" prepared by approximately threefold (mass) dilution with ion-exchanged water (a 10% by mass aqueous solution of neutral pH 7 detergent for cleaning precision gauges a nonionic surfactant, an anionic surfactant and an organic skeleton former from Wako Pure Chemical Industries, Ltd.).
• (3) An "Ultrasonic Dispersion System Tetora 150" (Nikkaki Bios Co., Ltd.) is prepared. This is an ultrasonic dispersion device with an electrical output of 120 W and is equipped with two oscillators (oscillation frequency = 50 kHz), which are arranged such that the phases are shifted by 180 °. About 3.3 L of ion-exchanged water is introduced into the water tank of this ultrasonic dispersion device and about 2 mL of Contaminon N is added to the water tank.
• (4) The cup described in (2) is set in the cup holder opening of the ultrasonic dispersion device, and the ultrasonic dispersion device is started. The height of the cup is set in such a manner that the resonance condition of the surface of the aqueous electrolyte solution in the cup is at a maximum.
• (5) While ultrasonically sonifying the aqueous electrolytic solution in the beaker used in (4), about 10 mg of the toner is added to the aqueous electrolytic solution in small aliquots, and the dispersion is carried out. The ultrasonic dispersion treatment is continued for an additional 60 seconds. The water temperature in the water bath is suitably controlled during the ultrasonic dispersion to be at least 10 ° C and not more than 40 ° C.
• (6) Using a pipette, the dispersed toner-containing electrolyte solution prepared in (5) is placed in the round-bottomed cup in the bottom rack as described in (1) with adjustment to provide a measurement concentration of about 5%. The measurement is then performed until the number of measured particles reaches 50,000.
• (7) The measurement data are analyzed by the previously cited software provided with the instrument and the weight average particle diameter (D4) is calculated. When set to degrees / volume% with the associated software, the "average diameter" on the "analysis / volumetric statistical value (arithmetic average)" screen is the weight average particle diameter (D4).

<Method for the measurement of the average roundness of the magnetic toner>

The average roundness of the magnetic toner is measured by the "FPIA-3000" (Sysmex Corporation) of a flow type particle image analyzer using the measurement and analysis conditions of the calibration method.

The specific measuring method is as follows. First, about 20 ml of ion-exchanged water, from which the solid impurities, etc. have been previously removed, is put in a glass container. To this is added as a dispersant about 0.2 mL of a dilution made by approximately threefold (mass) dilution with ion-exchanged water of "Contaminon N" (a 10% by mass aqueous solution of a neutral pH 7 detergent for the purification of precision measuring instruments prepared with a nonionic surfactant, an anionic surfactant and an organic scaffold, from Wako Pure Chemical Industries, Ltd.). About 0.02 g of the measurement sample is also added and a dispersion treatment is carried out for 2 minutes using an ultrasonic dispersion apparatus to provide a dispersion to be subjected to measurement. Cooling takes place during this treatment as appropriate to provide a dispersion temperature of at least 10 ° C and not more than 40 ° C. The ultrasonic dispersion device used here is a desktop ultrasonic cleaner / disperser having an oscillation frequency of 50 kHz and an electrical output of 150 W (for example, a "VS-150" of Velvo-Clear Co., Ltd.); a prescribed amount of ion-exchanged water is put in the water tank and about 2 ml of the aforementioned contaminon N is also added to the water tank.

The previously cited flow-type particle image analyzer (equipped with a standard objective lens (10X)) is used for the measurement, and a particle sheath "PSE-900A" (Sysmex Corporation) is used for the sheath solution. The dispersion prepared according to the procedure described above is introduced into the flow-type particle image analyzer, and 3000 of the magnetic toner are measured according to the total count mode in the HPF measurement mode. The average roundness of the magnetic toner is determined by the binarization threshold set to 85% during particle analysis and the particle diameter limited to a circle equivalent diameter of at least 1.985 μm to less than 39.69 μm.

For this measurement, an automatic focus adjustment is performed prior to the start of the measurement using latex particles (eg, an ion-exchanged water solution from "RESEARCH AND TESTPARTICLES Latex Microsphere Suspension 5200A" from Duke Scientific). Thereafter, the focal point adjustment is preferably performed every two hours after the start of the measurement.

In the present invention, the flow-type particle image analyzer used was calibrated by Sysmex Corporation and obtained a calibration certificate from Sysmex Corporation. The measurements were made under the same measurement and analysis conditions as the calibration certificate, except that the analyzed particle diameter is limited to a circle equivalent diameter of at least 1.985 μm to less than 39.69 μm.

The "FPIA-3000" flow-type particle image analyzer (Sysmex Corporation) uses a measuring principle based on taking a still image of the flowing particles and performing the image analysis. The sample added to the sample chamber is introduced through a sample syringe into a shallow sheath flow cell. The sample supplied to the shallow jacket flow is inserted between the sheath liquid through the sheath liquid to form a shallow flow. The sample passing through the shallow mantle flow cell is exposed to a stroboscopic light at an interval of 1/60 second, thus allowing photography of a still image of the flowing particles. In addition, since a shallow flow occurs, the photograph is taken under sharply adjusted conditions. The particle image is photographed with a CCD camera; the photographed image is subjected to image processing at an image processing resolution of 512 × 512 pixels (0.37 × 0.37 μm per pixel); the contour definition is performed on each particle image; and among other things, the projected area S and the peripheral length L are measured on the particle image.

The circle-equivalent diameter and the roundness are then determined using this area S and the peripheral length L. The circle-equivalent diameter is the diameter of the circle which has the same area as the projected area of the particle image. The roundness is provided as the value by dividing the circumference of the circle determined from the circle-equivalent diameter by the peripheral length of the projected image of the particle, and is calculated using the following formula. Roundness = 2 × (π × S) ^1/2 / L.

The roundness is 1,000 when the particle image is a circle, and the value of the roundness decreases as the degree of the irregularity of the periphery of the particle image increases. After the roundness of each particle is calculated, 800 in the roundness range of 0.200 to 1.000 are fractionated out; the arithmetic average of the obtained roundnesses is calculated; and this value is used as the average roundness.

<Measurement of weight average molecular weight (Mw) and radius of gyration (Rw) using size exclusion chromatography with a multi-angle laser light scattering (SEC-MALLS)>

0.03 g of the magnetic toner is dispersed in 10 mL of orthodichlorobenzene followed by shaking at 135 ° C for 24 hours using a shaker. Then filtration is performed using a 0, 2 μm filters, the ortho-dichlorobenzene-soluble material in the magnetic toner is obtained as the filtrate, and the measurement is carried out using this filtrate as the sample and using the following analytical conditions. [Analytical Conditions] separation column : TSKgel GMHHR-H (20) HT × 2 (Tosoh Corporation) column temperature : 135 ° C Mobile phase solvents : Orthodichlorobenzene Speed of the mobile phase : 1.0 mL / min sample concentration : about 0.3% injection amount : 300 μL Detector 1 : Multi-angle Light Scattering Detector (Wyatt DAWN EOS: Wyatt Technology Corporation) Detector 2 : Differential refractive index detector (Shodex RI-71: Showa Denko Kabushiki Kaisha)

The weight-average molecular weight (Mw) and the inertia radius (Rw) were determined by analyzing the obtained measurement results with the analytical software ASTRA for Windows (registered trademark) 4.73.04 (Wyatt Technology Corporation).

<Method for Measurement of Magnetic Toner Viscosity Using a Flow Tester / Temperature Rise Method>

The viscosity of the magnetic toner at 110 ° C by a flow tester / temperature rise method is determined as follows.

The measurement is performed by the following procedure using a Flow Tester Model CFT-500A (Shimadzu Corporation).

1.00 g of the samples were weighed. Using a former, it is pressed for 1 minute at a load of 10 MPa. Using this pressed sample, the viscosity is measured at 110 ° C at normal temperature and normal humidity (temperature about 20 to 30 ° C, humidity 30 to 70% RH) using the aforementioned measuring instrument and the conditions given below. The temperature rise method is used for the measurement method. RATE TEMP 4.0 D / M (° C / min) SET TEMP 50.0 DEG (° C) MAX TEMP 200.0 DEG INTERVAL 4.0 DEG PREHEAT 300.0 SEC (sec) LOAD 10.0 KGF (kg) THE (DIA) 1.0 MM (mm) THE (LENG) 1.0 MM PLUNGER 1.0 CM ² (cm ² )

[Examples]

The present invention will be described in more detail by the following Examples and Comparative Examples. The "parts" and "%" in the following description are, unless otherwise specified, in all cases based on mass.

<Production Example of Low Molecular Weight Polymer (L-1)>

Three hundred parts by weight of xylene was charged in a four-necked flask and heated to reflux, and a mixture of 80 parts by weight of styrene, 20 parts by weight of n-butyl acrylate and 2 parts by weight of di-tert-butyl peroxide as a polymerization initiator was added dropwise over 5 hours to obtain a solution of the low molecular weight polymer (L. -1).

<Production Example of High Molecular Weight Polymer (Type H-1)>

A high molecular weight polymer designated as high molecular weight polymer (Type H-1) was prepared by using the monomer, polymerization initiator and chain transfer agent shown in Table 1 and adjusting the reaction temperature, amount of the polymerization initiator and amount of the chain transfer agent.

An example of the production of a high molecular weight polymer (H-1) is as follows. 180 parts by weight of degassed water and 20 parts by weight of a 2% by weight aqueous solution of polyvinyl alcohol were added to a four-necked flask, followed by addition of a mixture of 75 parts by weight of stryol monomer 1, 25 parts by weight of n-butyl acrylate monomer 2, 0.005 part by weight of divinylbenzene Crosslinker, 1.0 part by mass of t-dodecylmercaptan as a chain transfer agent and 3.0 parts by mass of benzoyl peroxide as a polymerization initiator and stirring to produce a suspension. The interior of the flask was thoroughly replaced with nitrogen; the temperature was raised to 85 ° C to conduct polymerization; and the polymerization was completed by high molecular weight polymer (H-1) by standing for 24 hours.

<Production Examples of High Molecular Weight Polymers (Type H-2) to (Type H-4)>

High molecular weight polymers (Type H-2) to (Type H-4) were obtained by proceeding in the same manner, but changing the monomer, the polymerization initiator and the chain transfer agent for a high molecular weight polymer (Type H-1) to that described in U.S. Pat Table 1 shown. [Table 1] High molecular weight species Monomer 1 Monomer 2 polymerization Chain transfer agents Type H-1 styrene monomer n-butyl acrylate benzoyl peroxide t-dodecylmercaptan Type H-2 styrene monomer n-butyl acrylate dilauroyl t-dodecylmercaptan Type H-3 styrene monomer 2-ethylhexyl acrylate benzoyl peroxide t-dodecylmercaptan Type H-4 styrene monomer n-butyl acrylate dilauroyl -

<Production Example of Styrene / n-Butyl Acrylate (St-nBa) Copolymer 1>

Twenty-five parts by mass of the high molecular weight polymer (H-1) was incorporated in 300 parts by mass of the uniform solution of the low molecular weight polymer (L-1), and thorough mixing was conducted under reflux. This was followed by distillative removal of the organic solvent to obtain a styrene / n-butyl acrylate copolymer 1. This binder resin has an acid value of 0 mg KOH / g, a hydroxyl value of 0 mg KOH / g, a glass transition temperature (Tg) of 56 ° C, and a Mw of 11000 and an Rw / Mw of 5.2.

<Preparation Examples of Styrene / n-Butyl Acrylate (St / nBA) Copolymers 2 to 28>

Styrene / n-butyl acrylate (St / nBA) Copolymers 2 to 28 were prepared according to the preparation of styrene / n-butyl acrylate (St / nBA) copolymer 1 but with changes in high molecular weight polymer as shown in Table 2. [Table 2]

<Magnetic Toner Particle Production Example 1>

Styrene / n-butyl acrylate copolymer 1 shown in Table 2 100.0 parts by mass Polyethylene wax 1 shown in Table 3 8.0 parts by mass • Magnetic body 95.0 parts by mass (Composition: Fe ₃ O _4, shape: spherical, number-related primary particle average particle diameter: 0.21 micrometers, magnetic properties of 795.8 kA / m: H _c = 5.5 kA / m, σ _s = 84.0 Am ² / kg and σ _r = 6.4 Am ² / kg) • T-77 charge control agent 1.0 parts by mass (Hodogaya Chemical Co., Ltd.)

The raw materials listed above were preliminarily mixed using a FM10C Henschel mixer (Mitsui Miike Chemical Engineering Machinery Co., Ltd.), and were then mixed with a Twin screw kneader / extruder (PCM-30, Ikegai Ironworks Corporation) set at a rotational speed of 200 rpm kneaded with the set temperature set to provide a direct temperature near the outlet of the kneaded material of 155 ° C.

The resulting melt-kneaded material was cooled; the cooled melt-kneaded material was coarsely pulverized with a cutter mill; the resulting coarsely pulverized material was finely pulverized using a Turbo Mill T-250 (Turbo Kogyo Co., Ltd.) at a feed rate of 20 kg / hr with a set air temperature to provide an exhaust gas temperature of 38 ° C; and classification follows by using a Coanda effect-based multifraction classifier to obtain a magnetic toner particle 1 having a weight-average particle diameter (D4) of 7.8 μm. The results are shown in Table 4.

<Magnetic Toner Particle Production Examples 2 to 48>

Magnetic toner particles 2 to 48 were obtained by the procedure as in Magnetic Toner Particle Production Example 1 but using the binder resin shown in Table 2 and the release agent shown in Table 3 and changes in the kind and content of the release agent in Magnetic Toner Particle Production Example 1 shown in Table 4. The production conditions of the magnetic toner particles 2 to 48 are shown in Table 4.

<Magnetic Toner Particle Production Example 49>

External addition before a hot-wind treatment process was carried out by mixing 100 parts by mass of magnetic toner particles 1 using a FM10C Henschel mixer (Mitsui Miike Chemical Engineering Machinery Co., Ltd.) with 0.5 parts by mass in the external magnetic mixing and mixing method Toner Production Example 1 used. The external addition conditions here were a rotation speed of 3000 rpm and a processing time of 2 minutes.

Then, after being subjected to this external addition before warm-wind treatment, the magnetic toner particles were subjected to surface modification using a Meteorainbow (Nippon Pneumatic Mfg. Co., Ltd.), which is a device that effects the surface modification of toner particles using a warm wind performs. The surface modification conditions were a feed feed rate of 2 kg / hr, a hot air flow rate of 700 L / min, and a hot-gas ejection temperature of 300 ° C. The magnetic toner particles 49 were obtained by conducting this warm-blast treatment.

<Magnetic Toner Particle Production Example 50>

The magnetic toner particle 50 was obtained by following the same procedure as in Magnetic Toner Particle Production Example 49, but in this case using 1.5 parts by mass for the addition amount of the silica fine particles in the external addition before the hot-wind treatment in Magnetic Toner Production Example 49. [Table 3] release agent Melting point (° C) Polyethylene wax 1 75 Polyethylene wax 2 60 Polyethylene wax 3 58 Polyethylene wax 4 90 Polyethylene wax 5 92 Polyethylene wax 6 80 Polyethylene wax 7 70 Ester wax (myristyl myristate) 43 [Table 4]

<Magnetic Toner Production Example 1>

An external addition and mixing procedure was carried out using the method described in U.S. Pat 4 in the magnetic toner particle 1 provided by the magnetic toner particle production example 1.

In this example, the diameter of the inner circumference of the main housing was 1 in the 4 shown device 130 mm; the equipment used had a volume for the processing room 9 of 2.0 × 10 ^-3 m ³ ; the nominal power for the drive component 8th was 5.5 kW; and the stirring member 3 had that in the 5 specified form. The overlap width d in the 5 between the stirring member 3a and the stirring member 3b was 0.25D with respect to the maximum width D of the stirring member 3 and the working space between the stirring member 3 and the inner circumference of the main body 1 was 3.0 mm.

100 parts by mass of the magnetic toner particles 1 and 2.00 parts by mass of the above-described silica fine particles 1 were incorporated in the above-described U.S. Pat 4 shown device introduced with the previously described device structure.

Silica fine particles 1 were obtained by treating 100 parts by mass of a silica having a BET specific surface area of 130 m ² / g and a number-average particle diameter (Dl) of primary particles of 16 nm with 10 parts by mass of hexamethyldisilazane and then 10 parts by mass of dimethylsilicone oil.

Premixing was performed after the introduction of the magnetic toner particles and the silica fine particles to uniformly mix the magnetic toner particles and the silica fine particles. The premix conditions were as follows: a power of the drive component 8th of 0.1 W / g (drive component 8th Rotation speed of 150 rpm) and a processing time of 1 minute.

The external addition and mixing process was carried out after premixing was completed. In view of the conditions for the external addition and mixing process, the processing time was 5 minutes and the peripheral speed of the extreme end of the stirring member 3 was set to give a constant power of the driving member 8 of 1.0 W / g (drive component 8th Rotational speed of 1800 rpm). The conditions for the external addition and mixing process are shown in Table 5.

After the external addition and mixing process, the coarse particles, etc. are removed using a circular vibrating sieve equipped with a sieve having a diameter of 500 mm and an aperture of 75 μm to obtain the magnetic toner 1. A value of 18 nm was obtained when the magnetic toner 1 was subjected to magnification and observation with a scanning electron microscope, and the number average particle diameter of the primary particles of the silica fine particles on the magnetic toner surface was measured. The external addition conditions and properties of the magnetic toner 1 are shown in Table 5 and Table 6, respectively.

<Magnetic Toner Production Example 2>

A magnetic toner 2 was obtained by following the same procedure as in Magnetic Toner Production Example 1 except that Silica Fine Particle 2 was used in place of Silica Fine Particle 1. Silica fine particles 2 were obtained by performing the same surface treatment as in silica fine particles 1 but on a silica having a BET specific surface area of 200 m ² / g and a number average particle diameter (Dl) of primary particles of 12 nm.

A value of 14 nm was obtained when the magnetic toner 2 was subjected to magnification and observation with a scanning electron microscope and the number average particle diameter of the primary particles of the silica fine particles on the magnetic toner surface was measured. The external addition conditions and the properties of the magnetic toner 2 are shown in Table 5 and Table 6.

<Magnetic Toner Production Example 3>

A magnetic toner 3 was obtained by following the same procedure as in Magnetic Toner Production Example 1 except that Silica Fine Particle 3 was used instead of Silica Fine Particle 1. Silica fine particles were obtained by performing the same surface treatment as with silica fine particles 1 but on a silica having a BET specific area of 90 m ² / g and having a primary particle number average particle diameter (D1) of 25 nm. A value of 28 nm was obtained when the magnetic toner 3 was subjected to magnification and observation with a scanning electron microscope, and the number average particle diameter of the primary particles of the silica fine particles on the magnetic toner surface was measured. The external addition conditions and the properties of the magnetic toner 3 are shown in Table 5 and Table 6.

<Magnetic Toner Production Example 4>

The magnetic toner 4 was prepared by following the same procedure as in Magnetic Toner Production Example 3, but in this case changing the addition amount of the silica fine particles 3 from 2.00 parts by weight in Magnetic Toner Production Example 3 to 1.80 parts by mass. The external addition conditions and properties for the magnetic toner 4 are shown in Tables 5 and 6.

<Magnetic Toner Production Examples 5 to 41 and 44 to 54 and Magnetic Toner Production Comparative Examples 1 to 17 and 19 to 32>

Magnetic toners 5 to 41 and 44 to 54 and comparative magnetic toners 1 to 17 and 19 to 32 were prepared by using the magnetic toner particles shown in Table 5 in the magnetic toner production example 1 in place of the magnetic toner particle 1 and performing corresponding external addition processing using the ones shown in Table 3 external donor recipes, external donors, and external donor conditions. The properties of the magnetic toners 5 to 41 and 44 to 54 and the comparative magnetic toners 1 to 17 and 19 to 32 are shown in Table 6.

Anatase titanium oxide fine particles (BET specific surface area: 80 m ² / g, number-average particle diameter (Dl) of the primary particles: 15 nm, treated with 12 mass% isobutyltrimethoxysilane) were used for the titanium oxide fine particles shown in Table 5, and alumina fine particles (BET specific surface area) : 80 m ² / g, number-average particle diameter (Dl) of the primary particles: 17 nm, treated with 10 mass% of isobutyltrimethoxysilane) were used for the aluminum fine particles shown in Table 5.

Table 5 indicates the proportions (mass%) of the silica fine particles for the addition of the titanium oxide fine particles and / or fine alumina particles in addition to the silica fine particles.

For the magnetic toners 14 and 15 and the comparative magnetic toners 11 to 15, premixing was not performed, and the external addition and mixing process was performed immediately after introduction.

The hybridizer shown in Table 3 is Hybridizer Model 5 (Nara Machinery Co., Ltd.) and the Henschel mixer shown in Table 3 is FM10C (Mitsui Miike Chemical Engineering Machinery Co., Ltd.).

<Magnetic Toner Production Example 42>

The external addition and mixing procedure was carried out according to the following procedure using the same device configuration (device in FIG 4 ) as in Magnetic Toner Production Example 1.

As shown in Table 5, the silica fine particles 1 (2.00 mass parts) added in Magnetic Toner Production Example 1 were changed to the silica fine particles 1 (1.70 mass parts) and titanium oxide fine particles (0.30 mass parts).

First, 100 parts by mass of magnetic toner particles 1, 0.70 parts by weight of. Silica fine particles and 0.30 parts by weight of the fine titanium oxide particles, and then the same pre-mixing as in Magnetic Toner Production Example 1 was carried out.

In the external addition and mixing process, which was carried out after the premixing was completed, the processing was carried out for a processing time of 2 minutes while adjusting the peripheral speed of the extreme end of the stirring member 3 To ensure a constant power of the drive component 8th of 1.0 W / g (drive component 8th Rotational speed of 1800 rpm), after which the mixing process was temporarily stopped. Then, the additional introduction of the remaining silica fine particles (1.0 part by mass based on 100 parts by mass of the magnetic toner particles 1) was again followed by processing for a processing time of 3 minutes during the adjustment of the peripheral speed of the extremity of the stirring member 3 To ensure a constant power of the drive component 8th of 1.0 W / g (drive component 8th Rotational speed of 1800 rpm) and thus gave a total external addition and mixing time of 5 minutes.

After the external addition and mixing process, the coarse particles, etc. were removed using a circular vibrating screen as in Magnetic Toner Production Example 1 to obtain the magnetic toner 42. The external addition conditions for the magnetic toner 42 are shown in Table 5, and the properties of the magnetic toner 42 are shown in Table 6.

<Magnetic Toner Production Example 43>

The external addition and mixing procedure was carried out according to the following procedure using the same device configuration (device in FIG 4 ) as in Magnetic Toner Production Example 1.

As shown in Table 5, the silica fine particles 1 (2.00 mass parts) added in Magnetic Toner Production Example 1 were changed to silica fine particles 1 (1.70 mass parts) and titania fine particles (0.30 mass parts).

First, 100 parts by mass of the magnetic toner particles 1 and 1.70 parts by mass of the silica fine particles were introduced and then the same pre-mixing as in the magnetic toner production example 1 was carried out.

In the external addition and mixing process performed, after the pre-mixing was completed, the processing was carried out for a processing time of 2 minutes, while the peripheral speed of the extreme end of the stirring member 3 was set so that a constant power of the drive component 8th of 1.0 W / g (drive component 8th Rotational speed of 1800 rpm), after which the mixing process was temporarily stopped. The additional incorporation of the remaining titanium oxide fine particles (0.30 mass parts based on 100 mass parts of the magnetic toner particle 1) was then carried out, followed by reprocessing for a processing time of 3 minutes, while the peripheral velocity of the extremity of the stirring member 3 was set to maintain a constant power of the drive component 8th of 1.0 W / g (drive component 8th Rotation speed of 1800 rpm), and thus gave a total external addition and mixing time of 5 minutes.

After the external addition and mixing process, the coarse particles, etc. were removed using a circular vibrating sorter as in Magnetic Toner Production Example 1 to obtain the magnetic toner 43. The external addition conditions for the magnetic toner 43 are shown in Table 5, and the properties of the magnetic toner 43 are shown in Table 6.

<Magnetic Toner Production Comparative Example 18>

[Tabelle 6-1]

[Tabelle 6-2]

A comparative magnetic toner 18 was obtained by following the same procedure as in Magnetic Toner Production Example 1 except that Silica Fine Particles 4 were used instead of Silica Fine Particles 1. The silica fine particles 4 were obtained by conducting the same surface treatment as with the silica fine particle 1 but on a silica having a BET specific surface area of 30 m ² / g and a number-average particle diameter (D1) of the primary particles of 51 nm. A value of 53 nm was obtained when the comparative magnetic toner was subjected to magnification and observation with a scanning electron microscope and the number average particle diameter of the primary particles of the silica fine particles on the magnetic toner surface was measured. The external addition conditions for the comparative magnetic toner 18 are shown in Table 5, and the characteristics of the comparative magnetic toner 18 are shown in Table 6.

[Table 6-1]

[Table 6-2]

<Example 1>

(The image forming apparatus)

The image forming apparatus was an LBP-3300 (Canon, Inc.) in which the printing speed was modified from 21 sheets / minute to 25 sheets / minute.

Using this modified apparatus and magnetic toner 1, a 4000-sheet image printing test was conducted in a one-sheet intermittent mode of horizontal lines at a pressure percentage of 1% in a normal temperature and normal humidity environment (25 ° C / 50% RH) , A4 paper of 80 g / m ² was used as the recording medium.

According to the results, a high density was obtained before and after the durability test, and a stable image could be obtained. The results of the evaluation are shown in Table 7.

In addition, by using the magnetic toner 1 and the same image forming apparatus modified to allow the fixing temperature to be set in the fixing unit, the printing property was evaluated by using 90 g / m ^{2 of} A4 paper in a normal temperature, normal humidity environment (temperature = 25 ° C, humidity = 50% RH). Further, according to these results, cold impression did not occur below 180 ° C, and the cold impression property was thus excellent. The results are given in Table 7.

The printing property was also evaluated using 90 g / m ² A4 paper in a low-temperature low-humidity environment (temperature = 15 ° C, humidity 50% RH). Further, according to these results, cold impression did not occur below 180 ° C, and the cold impression property was thus excellent. The results are given in Table 7.

The evaluation methods and associated scales used in the evaluations made in the Examples and Comparative Examples of the present invention will be described below.

<Image density>

A continuous image area was formed for the image density, and the density of this continuous image area was measured by a MacBeth reflection densitometer (MacBeth Corporation).

A:

sehr gut (größer als oder gleich 1,46)

B:

gut (weniger als oder gleich 1,45 und größer als oder gleich 1,41) (von einem praktischen Standpunkt nicht problematisch)

C:

mittel (weniger als oder gleich 1,40 und größer als oder gleich 1,36) (nicht bevorzugt, aber ein akzeptables Niveau von einem praktischen Standpunkt)

D:

schlecht (weniger als oder gleich 1,35)

The following scale was used to obtain the reflection density of the solid image at the beginning of the durability test (rating 1) and after 4,000 sheets were printed (rating 2).

A:

very good (greater than or equal to 1.46)

B:

good (less than or equal to 1.45 and greater than or equal to 1.41) (not problematic from a practical standpoint)

C:

average (less than or equal to 1.40 and greater than or equal to 1.36) (not preferred, but an acceptable level from a practical standpoint)

D:

bad (less than or equal to 1.35)

<Cold offset>

A:

kalter Abdruck trat immer noch nicht bis 180°C auf

B:

kalter Abdruck trat auf von größer oder gleich 180°C bis weniger als 190°C (nicht problematisch von einem praktischen Standpunkt)

C:

kalter Abdruck trat auf von mehr als oder gleich 190°C bis weniger als 200°C (nicht bevorzugt, aber ein akzeptables Niveau von einem praktischen Standpunkt)

D:

kalter Abdruck trat auf bei größer oder gleich 200°C

The development bias was set so that the image density of a halftone image measured by a MacBeth reflection densitometer (MacBeth Corporation) was 0.80 to 0.85. Then, the fixing unit was cooled to room temperature (25 ° C or 15 ° C) the heater temperature in the fixing unit was set to be in the range of greater than or equal to 160 ° C to less than or equal to 230 ° C (hereinafter referred to as the fixing temperature); and power was supplied and the image was injected after six minutes and fixing was performed. The cold impression was evaluated by visual inspection using the following scale.

A:

cold impression still did not occur up to 180 ° C

B:

cold impression occurred from greater than or equal to 180 ° C to less than 190 ° C (not problematic from a practical standpoint)

C:

cold impression occurred from greater than or equal to 190 ° C to less than 200 ° C (not preferred, but an acceptable level from a practical standpoint)

D:

cold impression occurred at greater than or equal to 200 ° C

<Examples 2 to 54 and Comparative Examples 1 to 32>

[Tabelle 7-2]

The toner ratings were conducted under the same conditions as in Example 1 using the magnetic toners 2 to 33 and the magnetic toner for comparison 1 to 32 for the magnetic toner. The results of the evaluations are shown in Table 7. For the comparative magnetic toners, images were obtained which posed parabolic problems in terms of image density and / or offset resistance. [Table 7-1]

[Table 7-2]

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the priority of Japanese Patent Application 2011-286062 , filed on Dec. 27, 2011, which is incorporated herein by reference in its entirety.

LIST OF REFERENCE NUMBERS

1

main body

2

rotating component

3, 3a, 3b

stirring member

4

coat

5

Raw material inlet port

6

Product discharge opening

7

central axis

8th

driving member

9

processing room

10

End surface of the rotating component

11

direction of rotation

12

reverse direction

13

forward direction

16

Raw material inlet port inner piece

17

Product delivery port inner piece

d

Distance showing the overlapping part of the stirring components

D

Rührbauteilbreite

100

an electrostatic image bearing member (photosensitive member)

102

Toner carrying component

103

developing sheet

114

Transfer member (transfer charge roller)

116

cleaning tank

117

Charge component (charge roller)

121

Laser generator (a latent image forming device, light exposure device)

123

laser

124

pick-up roller

125

conveyor belt

126

fuser

140

developing device

141

stirring member

Claims (4)

A magnetic toner comprising: magnetic toner particles comprising a binder resin and a magnetic body, and inorganic fine particles present on the surface of the magnetic toner particles, wherein; the inorganic fine particles present on the surface of the magnetic toner particles comprise metal oxide fine particles, the metal oxide fine particles containing silica fine particles and optionally containing titanium oxide fine particles and alumina fine particles, and a content of the silica fine particles of at least 85 mass% based on the total mass of the silica fine particles, the titania fine particles and the alumina fine particles; in which; when a coverage ratio A (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles, and a coverage ratio B (%) is a coverage ratio of the surface of the magnetic toner particles by the inorganic fine particles fixed to the surface of the magnetic toner particles; the magnetic toner has a coverage ratio A of at least 45.0% and not more than 70.0% and a ratio [coverage ratio B / coverage ratio A] of the coverage ratio B to the coverage ratio A of at least 0.50 and not more than 0.85 and the binder resin is a styrenic resin; for a weight average molecular weight (Mw) and a radius of gyration (Rw) measured on the ortho-dichlorobenzene-soluble magnetic toner material using size-exclusion chromatography with multi-angle laser light scattering (SEC-MALLS), the weight average molecular weight (Mw) of at least 5,000 to not is more than 20,000, and the ratio [Rw / Mw] of this radius of gyration (Rw) to the weight average molecular weight (Mw) is at least 3.0 × 10 ^-3 to not more than 6.5 × 10 ^-3 ; and the viscosity of the magnetic toner at 110 ° C measured by a flow tester / temperature rise method is at least 5,000 Pa · s to not more than 25,000 Pa · s. A magnetic toner according to claim 1, wherein the weight average molecular weight (Mw) is from at least 5,000 to not more than 20,000, and the ratio [Rw / Mw] of the radius of gyration (Rw) to the weight average molecular weight (Mw) is at least 5.0 × 10 ^-3 to not more than 6.5 × 10 ^-3 . A magnetic toner according to claim 1 or 2, wherein the coefficient of variation of the coverage ratio A is not more than 10.0%. The magnetic toner according to any one of claims 1 to 3, wherein the magnetic toner particle additionally comprises a release agent, and this release agent is a hydrocarbon wax.

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